THE    MICROSCOPIST. 


•IOLOGY 
LIBRARY 


ZENTMAYER'S  AMERICAN  CENTENNIAL  STAND 


THE 


MICROSCOPIST: 


MANUAL  OF  MICROSCOPY, 


AND 


COMPENDIUM    OF    THE  MICROSCOPIC  SCIENCES;   MICRO- 
MINEKALOGY,  MICKO-CHEMISTEY,  BIOLOGY,  HIS- 
TOLOGY, AND  PRACTICAL  MEDICINE. 


FOURTH    EDITION, 
GREATLY    ENLARGED, 

WITH 

TWO    HUNDRED    AND    FIFTY-TWO    ILLUSTRATIONS. 


BY 

J.  H.  WYTHE,  A.M.,  M.D., 

PROFESSOR  OF  MICROSCOPY  AND  HISTOLOGY  IN  THE  MEDICAL  COLLEGE  OP  THE 
PACIFIC,  SAN  FRANCISCO,  CAL. 


PHILADELPHIA: 
LINDSAY    &    BLAKISTON. 

1880. 


Entered,  according  to  Act  of  Congress,  in  the  year  1880, 

By  LINDSAY  &  BLAKISTON, 
In  the  Office  of  the  Librarian  of  Congress,  at  Washington,  D.  C. 


SHERMAX  &  CO.,  PRINTERS, 
PHILADELPHIA. 


•*       4T, 


KESPECTFULLY    DEDICATED 

TO  THE 

SAN  FRANCISCO  MICROSCOPICAL  SOCIETY, 

AS   A   TESTIMONY 

TO   THE 

ZEAL  AND  INDUSTRY  OF  ITS  MEMBERS 

IN 

THE  PROSECUTION 

OF 

MICROSCOPIC    SCIENCE. 


PREFACE. 


THE  first  and  second  editions  of  this  work,  in  1851  and 
1853,  were  intended  to  furnish  a  manual  on  the  use  of  the 
microscope  for  physicians  and  naturalists.  The  third  and 
present  editions  aim  to  be  also  a  compendium  of  the  micro- 
scopic sciences,  but  as  microscopy  reaches  its  climax  in  prac- 
tical medicine  this  branch  of  study  receives  the  largest 
attention.  Matters  of  mere  curiosity  have  been  but  briefly 
referred  to,  while  every  necessary  fact  or  principle  relating  to 
the  microscope  has  been  carefully  stated  and  classified. 

By  the  liberality  of  the  publishers,  the  chapters  on  the  use 
of  the  microscope  in  Pathology,  Diagnosis,  and  Etiology, 
which  have  been  added  to  this  edition,  have  been  largely  illus- 
trated with  woodcuts  from  Kindfleisch. 

The  Index  and  Glossary  have  been  combined  in  this  edition 
so  as  to  be  a  source  of  valuable  information,  and  notices  of 
recent  additions  to  the  microscope,  together  with  the  genera  of 
microscopic  plants,  have  been  given  in  an  Appendix. 

No  pains  have  been  spared  to  render  this  manual  a  useful 
companion  to  the  student  of  Nature,  and  an  aid  to  the  progress 
of  real  science. 

July,  1880. 


CONTENTS. 


CHAPTER  I. 
HISTORY  AND  IMPORTANCE  OF  MICROSCOPY. 

Application  of  the  Microscope  to  Science  and  Art — Progress  of  Micros- 
copy, 17-21 

CHAPTER  II. 
THE  MICROSCOPE. 

The  Simple  Microscope — Chromatic  and  Spherical  Aberration — Compound 
Microscope — Achromatic  Object-glasses — Eye-pieces — Mechanical  Ar- 
rangements— Binocular  Microscope,  .....  21-32 

CHAPTER  III. 
MICROSCOPIC  ACCESSORIES. 

Diaphragms— Condensers — Oblique  Illuminators — Dark-ground  ditto — Il- 
lumination of  Opaque  Objects— Measuring  and  Drawing  Objects — 
Standards  of  Measurement — Moist  Chamber — Gas  Chamber — Warm 
Stage — Polariscope — Microspectroscope — Nose-piece — Object-finders — 
Micro-photography,  . 32-48 

CHAPTER  IV. 

USE  OF  THE  MICROSCOPE. 

Care  of  the  Instrument— Care  of  the  Eyes — Table — Light — Adjustments — 
Errors  of  Interpretation — Testing  the  Microscope,  .  .  .  48-58 


X  CONTENTS. 

CHAPTEE  V. 

MODERN  METHODS  OF  EXAMINATION. 

Preliminary  Preparation  of  Objects — Minute  Dissection — Preparation  of 
Loose  Textures — Preparation  by  Teasing — Preparation  by  Section — 
Staining  Tissues — Injecting  Tissues — Preparation  in  Viscid  Media — 
Fluid  Media — Indifferent  Fluids — Chemical  Eeagents — Staining  Fluids 
— Injecting  Fluids — Preservative  Fluids — Cements,  .  .  58-76 

CHAPTEE  VI. 

MOUNTING  AND  PRESERVING  MICROSCOPIC  OBJECTS. 

Opaque  Objects — Cells — Dry  Objects — Mounting  in  Balsam  or  Dammar — 
Mounting  in  Fluid— Cabinets — Collecting  Objects — Aquaria,  76-83 

CHAPTEE  VII. 

THE  MICROSCOPE  IN  MINERALOGY  AND  GEOLOGY. 

Preparation  of  Specimens — Examination  of  Specimens — Crystalline  Forms 
— Crystals  within  Crystals— Cavities  in  Crystals — Use  of  Polarized 
Light — Origin  of  Eock  Specimens — Materials  of  Organic  Origin — 
Microscopic  Palaeontology, 84-98 

CHAPTEE  VIII. 
THE  MICROSCOPE  IN  CHEMISTRY. 

Apparatus  and  Modes  of  Investigation — Preparation  of  Crystals  for  the 
Polariscope — Use  of  the  Microspectroscope — Inverted  Microscope — 
General  Micro-chemical  Tests — Determination  of  Substances — Al- 
kalies— Acids — Metallic  Oxides — Alkaloids — Crystalline  Forms  of 
Salts, 98-115 

CHAPTEE  IX. 
THE  MICROSCOPE  IN  BIOLOGY. 

Theories  of  Life — Elementary  Unit  or  Cell — Cell-structure  and  Formation 
— Phenomena  of  Bioplasm — Movements  of  Cells — Microscopic  Dem- 
onstration of  Bioplasm — Chemistry  of  Cells  and  their  Products — Va- 
rieties of  Bioplasm — Cell-genesis — Eeproduction  in  Higher  Organisms 
— Alternation  of  Generations — Parthenogenesis — Transformation  and 
Metamorphosis — Discrimination  of  Living  Forms,  .  .  116-127 


CONTENTS.  XI 

CHAPTEK  X. 

THE  MICROSCOPE  IN  VEGETABLE  HISTOLOGY  AND  BOTANY. 

Molecular  Coalescence — Cell-substance  in  Vegetables — Cell-wall  or  Mem- 
brane— Ligneous  Tissue — Spiral  Vessels — Laticiferous  Vessels — Sili- 
ceous Structures — Formed  Material  in  Cells — Forms  of  Vegetable  Cells 
— Botanical  Arrangement  of  Plants — Fungi — Protophytes — Desmids — 
Diatoms — Nostoc — Oscillatoria — Examination  of  the  Higher  Crypto- 
gamia — Examination  of  Higher  Plants,  ....  128-157 


CHAPTER  XL 

THE  MICROSCOPE  IN  ZOOLOGY. 

Monera — Rhizopods — Infusoria — Rotatoria — Polyps — Hydroids — Acalephs 
— Echinoderms  —  Bryozoa  —  Tunicata  —  Conchifera  —  Gasteropoda — 
Cephalopoda — Entozoa — Annulata — Crustacea — Insects — Arachnida — 
Classification  of  the  Invertebrata,  .  .  . ,  .  .  158-182 


CHAPTER  XII. 

THE  MICROSCOPE  IN  ANIMAL  HISTOLOGY. 

Histo-chemistry — Histological  Structure — Simple  Tissues — Blood — Lymph 
and  Chyle — Mucus — Epithelium — Hair  and  Nails — Enamel — Connec- 
tive Tissues — Compound  Tissues — Muscle — Nerve — Glandular  and 
Vascular  Tissue — Development  of  the  Tissues — Digestive  and  Circu- 
latory Organs — Secretive  Organs — Respiratory  Organs — Generative 
Organs — Locomotive  Organs — Sensory  Organs — Organs  of  Special 
Sense— Suggestions  for  Practice, 182-226 


CHAPTER  XIII. 

THE  MICROSCOPE  IN  PATHOLOGY. 

Preparation  of  Specimens — The  Appearance  of  Tissues  after  Death — De- 
generation of  Tissues — The  Metamorphoses — The  Infiltrations — In- 
flammation— Resolution  and  Organization — Pathological  New  Forma- 
tions— New  Formation  of  Pathological  Cells — Pathological  Growths  of 
Higher  Animal  Tissues — Pathological  Growths  of  Connective  Tissue 
Origin— Pathological  Growths  of  Epithelial  Origin,  .  .  226-295 


Xll  CONTENTS. 

CHAPTER  XIV. 
THE  MICROSCOPE  IN  DIAGNOSIS. 

The  Blood  in  Disease — Examination  of  Urine — Urea — Chlorides — Bile — 
Albumen — Sugar — Urinary  Deposits — Epithelium-^Mucus  and  Pus — 
Blood — Spermatozoa — Bacteria,  Fungi,  etc. — Tube-casts — Crystalline 
and  Amorphous  Deposits — Pus  and  Mucus  in  Diagnosis — Examination 
of  Milk — Saliva  and  Sputum — Vomited  Matters — Intestinal  Discharges 
— Vaginal  Discharges, 295-320 

CHAPTEE  XV. 

THE  MICROSCOPE  IN  ^ETIOLOGY. 

Examination  of  the  Air — Examination  of  Soil  and  Water — Examination 
of  Food,  etc. — Parasites— Vegetable  Parasites  or  Epiphytes— Fungi — 
Dust  or  Germ  Fungi,  Conio  or  Gymnomycetes — Filamentous  Fungi, 
Hyphomycetes — Cleft  Fungi,  Schizomycetes — Mould  Diseases— Fungi 
of  True  Parasitic  Diseases  of  the  Skin  and  Mucous  Membranes — 
Fungi  as  Excitors  of  Fermentation  and  Putrefaction  and  Causes  of 
Disease — Animal  Parasites  —  Protozoa  — Vermes — Arthropoda — Dis- 
ease Germs, 321-344 

APPENDIX — Improvements  in  Microscopes  and  in  Preparations — Genera 
of  Cryptogamia, 345-399 

INDEX  AND  GLOSSARY,       .        .        .        .        .  ,    401-434 


THE  MICROSCOPIST. 


CHAPTER    I. 

HISTORY   AND   IMPORTANCE    OF   MICROSCOPY. 

THE  term  microscopy,  meaning  the  use  of  the  micro- 
scope, is  also  applied  to  the  knowledge  obtained  by  this 
instrument,  and  in  this  "sense  is  commensurate  with  a 
knowledge  of  the  minute  structure  of  the  universe,  so  far 
as  it  may  come  under  human  observation.  Physics  and 
astronomy  treat  of  the  general  arrangement  and  motions 
of  masses  of  matter,  chemistry  investigates  their  constitu- 
tion, and  microscopy  determines  their  minute  structure. 
The  science  of  histology,  so  important  to  anatomy  and 
physiology,  is  wholly  the  product  of  microscopy,  while 
this  latter  subject  lends  its  aid  to  almost  every  other 
branch  of  natural  science. 

To  the  student  of  physical  phenomena  this  subject  un- 
folds an  amazing  variety  developed  from  most  simple 
beginnings,  while  to  the  Christian  philosopher  it  gives  the 
clearest  evidence  of  that  Creative  Power  and  Wisdom 
before  whom  great  and  small  are  terms  without  meaning. 

In  the  arts,  as  well  as  in  scientific  investigations,  the 
microscope  is  used  for  the  examination  and  preparation  of 
delicate  work.  The  jeweller,  the  engraver,  and  the  miner 
find  a  simple  microscope  almost  essential  to  their  employ- 
ments. This  application  of  the  magnifying  power  of  lenses 
was  known  to  the  ancients,  as  is  shown  by  the  glass  lens 

2 


18  THE    MICROSCOPIST. 

found  at  Mneveh,  and  by  the  numerous  gems  and  tablets 
so  finely  engraved  as  to  need  a  magnifying  glass  to  detect 
their  details. 

In  commerce,  the  microscope  has  been  used  to  detect 
adulterations  in  articles  of  food,  drugs,  and  manufactures. 
In  a  single  year  $60,000  worth  of  adulterated  drugs  was 
condemned  by  the  New  York  inspector,  and,  so  long  as 
selfishness  is  an  attribute  of  degraded  humanity,  so  long 
will  the  microscope  be  needed  in  this  department. 

In  agriculture  and  horticulture  microscopy  affords  valu- 
able assistance.  It  has  shown  us  that  mildew  and  rust  in 
wheat  and  other  food-grains,  the  "  potato  disease,"  and 
the  "  vine  disease,"  are  dependent  on  the  growth  of  minute 
parasitic  fungi.  It  has  also  revealed  many  of  the  minute 
insects  which  prey  upon  our  grain-bearing  plants  and  fruit 
trees.  The  damage  wrought  by  these  insects  in  the  United 
States  alone  has  been  estimated  by  competent  observers 
as  not  less  than  three  hundred  millions  of  dollars  in  each 
year.  The  muscardine,  which  destroys  such  large  num- 
bers of  silk-worms  in  France  and  other  places,  is  caused 
by  a  microscopic  fungus,  the  Botrytis  bassiana. 

The  mineralogist  determines  the  character  of  minute 
specimens  or  of  thin  sections  of  rock,  and  the  geologist 
finds  the  nature  of  many  fossil  remains  by  their  magnified 
image  in  the  microscope. 

The  chemist  recognizes  with  this  instrument  excessively 
minute  quantities  and  reactions  which  would  otherwise 
escape  observation.  Dr.  Wormley  shows  that  micro- 
chemical  analysis  detects  the  reaction  of  the  10,000th  to 
the  100,000th  part  of  a  grain  of  hydrocyanic  acid,  mer- 
cury, or  arsenic,  and  very  minute  quantities  of  the  vege- 
table alkaloids  may  be  known  by  a  magnified  view  of  their 
sublimates.  The  micro-spectroscope  promises  still  more 
wonderful  powers  of  analysis  by  the  investigation  of  the 
absorption  bands  in  the  spectra  of  different  substances. 

In  biology  the  wonderful  powers  of  the  microscope  find 


HISTORY    AND    IMPORTANCE    OF    MICROSCOPY.          19 

their  widest  range.  If  we  see  not  life  itself,  we  see  its 
first  beginnings,  and  the  process  of  its  development  or 
manifestation.  If  we  see  not  Nature  in  her  undress,  we 
trace  the  elementary  warp  and  woof  of  her  mystic  drapery. 

In  vegetable  and  animal  physiology  we  see,  by  its 
means,  not  only  the  elementary  unit^the  foundation-stone 
of  the  building — but  also  chambers  and  laboratories  in 
the  animated  temple,  which  we  should  never  have  sus- 
pected— tissues  and  structures  not  otherwise  discoverable 
— not  to  speak  of  species  innumerable  which  are  invisible 
to  the  naked  eye. 

In  medical  science  and  jurisprudence  the  contributions 
of  microscopy  have  been  so  numerous  that  constant  study 
in  this  department  is  needed  by  the  physician  who  would 
excel  or  even  keep  pace  with  the  progress  of  his  profes- 
sion. Microscopy  may  be  truly  called  the  guiding  genius 
of  medical  science. 

Even  theology  has  its  contribution  from  microscopy. 
The  teleological  view  of  nature,  which  traces  design,  re- 
ceives from  it  a  multitude  of  illustrations.  In  this  de- 
partment the  war  between  skeptical  philosophy  and  theol- 
ogy has  waged  most  fiercely ;  and  if  the  difference  between 
living  and  non-living  matter  may  be  demonstrated  by  the 
microscope,  as  argued  by  Dr.  Beale  and  others,  theology 
sends  forth  a  paean  of  victory  from  the  battlements  of  this 
science. 

The  attempts  made  by  early  microscopists  to  determine 
ultimate  structure  were  of  but  little  value  from  the  im- 
perfections of  the  instruments  employed,  the  natural  mis- 
takes made  in  judging  the  novel  appearances  presented, 
and  the  treatment  to  which  preparations  were  subjected. 
In  late  years  the  optical  and  mechanical  improvements  in 
microscopes  have  removed  one  source  of  error,  but  other 
sources  still  remain,  rendering  careful  attention  to  details 
and  accurate  judgment  of  phenomena  quite  essential.  Care- 
ful manipulation  and  minute  dissection  require  a  knowledge 


20  THE    MICROSCOPIST. 

of  the  effects  of  various  physical  and  chemical  agencies,  a 
steady  hand,  and  a  quick-discerning  eye.  Above  all, 
microscopy  requires  a  cultured  mind,  capable  of  readily 
detecting  sources  of  fallacy,  and  such  a  love  of  truth  as 
enables  a  man  to  free  himself  from  all  preconceived  no- 
tions of  structure  and  from  all  bias  in  favor  of  particular 
theories  and  analogies.  What  result  is  it  possible  to  draw 
from  the  observations  of  those  who  boil,  roast,  macerate, 
putrefy,  triturate,  and  otherwise  injure  delicate  tissues, 
except  for  the  purpose  of  isolating  special  structures  or 
learning  the  effects  of  such  agencies  ?  Yet  many  of  the 
phenomena  resulting  from  such  measures  have  been  de- 
scribed as  primary,  and  theories  of  development  have  been 
proposed  on  the  basis  of  such  imperfect  knowledge. 

Borelli  (1608-1656)  is  considered  to  be  the  first  who 
applied  the  microscope  to  the  examination  of  animal 
structure.  Malpighi  (1661)  first  witnessed  the  actual  cir- 
culation of  the  blood,  which  demonstrated  the  truth  of 
Harvey's  reasoning.  He  also  made  many  accurate  obser- 
vations in  minute  anatomy.  Lewenhoeck,  Swammerdam, 
Lyonet,  Lieberkuhn,  Hewson,  and  others,  labored  also  in 
this  department.  When  we  remember  that  these  early 
laborers  u;ed  only  simple  microscopes,  generally  of  their 
own  construction,  we  must  admire  their  patient  industry, 
skilful  manipulation,  and  accurate  judgment.  In  these 
respects  they  are  models  to  all  microscopists. 

Within  the  last  quarter  of  a  century  microscopic  ob- 
servers may  be  numbered  by  thousands,  and  some  have 
attained  an  eminent  reputation.  At  the  present  day,  in 
Germany,  England,  France,  and  the  United  States,  the 
most  careful  and  elaborate  investigations  are  being  made, 
older  observations  are  repeated  and  corrected,  new  discov- 
eries are  rapidly  announced,  and  the  most  hidden  recesses 
of  nature  are  being  explored. 

It  is  proposed  in  this  treatise  to  give  such  a  resume  of 
microscopy  as  shall  enable  the  student  in  any  department 


THE    MICROSCOPE.  21 

to  pursue  original  investigations  with  a  general  knowl- 
edge of  what  has  been  accomplished  by  others.  To  this 
end  a  comprehensive  view  of  the  necessary  instruments 
and  details  of  the  art,  or  what  the  Germans  call  technol- 
ogy, is  first  given,  and  then  a  brief  account  of  the  appli- 
cation of  the  microscope  to  various  branches  of  science, 
especially  considering  the  needs  of  physicians  and  stu- 
dents of  medicine. 


CHAPTER   II. 

THE    MICROSCOPE. 

The  Simple  Microscope. — The  magnifying  power  of  a 
glass  lens  (from  lens,  a  lentil ;  because  made  in  the  shape 
of  its  seeds)  was  doubtless  known  to  the  ancients,  but  only 
in  modern  times  has  it  been  applied  in  scientific  research. 

The  forms  of  lenses  generally  used  are  the  double  convex, 
with  two  convex  faces ;  piano  convex,  with  one  face  flat 
and  the  other  convex ;  double  concave,  with  two  concave 
faces ;  plano-concave,  with  one  flat  and  one  concave  face  ; 
and  the  meniscus,  with  a  concave  and  a  convex  face. 

In  the  early  part  of  the  seventeenth  century  very  mi- 
nute lenses  were  used,  and  even  small  spherules  of  glass. 
Many  of  the  great  discoveries  of  that  period  were  made 
by  these  means.  A  narrow  strip  of  glass  was  softened  in 
the  flame  of  a  spirit-lamp  and  drawn  to  a  thread,  on  the 
end  of  which  a  globule  was  melted  and  placed  in  a  thin 
folded  plate  of  brass,  perforated  so  as  to  admit  the  light. 
Some  of  these  globules  were  so  small  as  to  magnify  sev- 
eral hundred  diameters.  Of  course,  they  were  inconve- 
nient to  use,  and  larger  lenses,  ground  on  a  proper  tool, 
were  more  common. 

The  magnifying  power  of  lenses  depends  on  a  few  simple 


22  THE    MICROSCOPIST. 

optical  laws,  concerning  refraction  of  light,  allowing  the 
eye  to  see  an  object  under  a  larger  visual  angle  ;  so  that 
the  power  of  a  simple  microscope  is  in  proportion  to  the 
shortness  of  its  focal  length,  or  the  distance  from  the  lens 
to  the  point  where  a  distinct  image  of  the  object  is  seen. 
This  distance  may  be  measured  by  directly  magnifying 
an  object  with  the  lens,  if  it  be  a  small  one,  or  by  casting 
an  image  of  a  distant  window,  candle,  etc.,  upon  a  paper 
or  wall.  The  focus  of  the  lens  is  the  point  where  the 
image  is  most  distinct.  Different  persons  see  objects 
naturally  at  different  distances,  but  ten  inches  is  consid- 
ered the  average  distance  for  the  minimum  of  distinct 
vision.  A  lens,  therefore,  of  two  inches  focal  length, 
magnifies  five  diameters  ;  of  one  inch  focus,  ten  diameters  ; 
of  one-half  inch,  twenty  diameters  ;  of  one-eighth  inch, 
eighty  diameters ;  etc. 

Simple  microscopes  are  now  seldom  used,  except  as 
hand  magnifiers,  or  for  the  minute  dissection  and  prepa- 
ration of  objects.  They  are  used  for  the  latter  purpose, 
when  suitably  mounted  with  a  convenient  arm,  mirror, 
etc.,  because  of  the  inconvenience  of  larger  and  otherwise 
more  perfect  instruments. 

Single  lenses,  of  large  size,  are  also  used  for  concentra- 
ting the  light  of  a  lamp  on  an  object  during  dissection,  or 
on  an  opaque  object  on  the  stage  of  a  compound  micro- 
scope. 

There  are  imperfections  of  vision  attending  the  use  of 
all  common  lenses,  arising  from  the  spherical  shape  of  the 
surface  of  the  lens,  or  from  the  separation  of  the  colored 
rays  of  light  when  passing  through  such  a  medium. 
These  imperfections  are  called  respectively  spherical  and 
chromatic  aberration.  To  lessen  or  destroy  these  aberra- 
tions, various  plans  have  been  proposed  by  opticians.  For 
reducing  spherical  aberration,  Sir  John  Herschel  pro- 
posed a  doublet  of  two  plano-convex  lenses,  whose  focal 
lengths  are  as  2.3  to  1,  with  their  convex  sides  together ; 


THE    MICROSCOPE.  23 

and  Mr.  Coddington  invented  a  lens  in  the  form  of  a 
sphere,  cut  away  round  the  centre  so  as  to  assume  the 
shape  of  an  hour-glass.  This  latter,  in  a  convenient  set- 
ting, is  one  of  the  best  pocket  microscopes.  Dr.  Wollas- 
ton's  doublet  consists  of  two  plano-convex  lenses,  whose 
focal  lengths  are  as  1  to  3,  with  the  plane  sides  of  each 
artd  the  smallest  lens  next  the  object.  They  should  be 


FIG.  1. 


Holland's  Triplet. 

about  the  difference  of  their  focal  lengths  apart,  and  a 
diaphragm  or  stop — an  opaque  screen  with  a  hole  in  it — 
placed  just  behind  the  anterior  lens.  This  performs  ad- 
mirably, yet  has  been  further  improved  by  Mr.  Holland 
by  making  a  triplet  of  plano-convex  lenses  (Fig.  1),  with 
the  stop  between  the  upper  lenses. 

The  Compound  Microscope  consists  essentially  of  two 
convex  lenses,  placed  some  distance  apart,  so  that  the 
image  made  by  one  may  be  magnified  by  the  other. 
These  are  called  the  object-glass  and  the  eye-glass.  In 
Fig.  2,  A  is  the  object-glass,  which  forms  a  magnified 
image  at  c,  which  is  further  enlarged  by  the  eye-glass  B. 
An  additional  lens,  D,  is  usually  added,  to  enlarge  the 
field  of  view.  This  is  called  the  field-glass.  Its  office,  as 
in  the  figure,  is  to  collect  more  of  the  rays  from  the 
object-glass  and  form  an  image  at  F,  which  is  viewed  by 
the  eye-glass. 

Owing  to  chromatic  aberration,  an  instrument  of  this 
kind  is  still  imperfect,  presenting  rings  of  color  round  the 
edge  of  the  field  of  view  as  well  as  at  the  edge  of  the 
magnified  image  of  an  object,  together  with  dimness  and 


24  THE    MICROSCOPIST. 

confusion  of  vision.  This  may  be  partly  remedied  by  a 
small  hole  or  stop  behind  the  object-glass,  which  reduces 
the  aperture  to  the  central  rays  alone,  yet  it  is  still  un- 

FIG.  2. 


Compound  Microscope. 


satisfactory.     Some  considerable  improvement  may  result 
from  using  Wollaston's  doublet  as  an  object-glass,  but  the 


THE    MICROSCOPE. 


25 


achromatic  object-glasses  now  supplied  by  good  opticians 
leave  nothing  to  be  desired. 

Objed-glasses. — A  general  view  of  an  achromatic  object- 
glass  is  given  in  Fig.  3.  It  is  a  system  of  three  pairs  of 
lenses,  1,  2,  8,  each  composed  of  a  double  convex  of  crown 
glass  and  a  plano-concave  of  flint,  a,  6,  c,  represents  the 
angle  of  aperture,  or  the  cone  of  rays  admitted.  It  is 
unnecessary  to  consider  the  optical  principles  which  un- 
derlie this  construction.  Different  opticians  have  different 
formulae  and  propose  various  arrangements  of  lenses,  and 
there  is  room  for  choice  among  the  multitude  of  micro- 
scopes presented  for  sale.  For  high  powers,  the  German 


FIG.  3. 


FIG.  4. 


Achromatic  Object-glass. 


Huygenian  Eye-piece. 


and  French  opticians  have  lately  proposed  a  principle  of 
construction  which  is  known  as  the  immersion  system. 
It  consists  in  the  interposition  of  a  drop  of  water  between 
the  front  lens  of  the  objective  and  the  covering  glass  over 
the  object.  This  form  of  object-glass  is  corning  into  gen- 
eral use.  For  the  more  perfect  performance  of  an  objec- 
tive, it  is  necessary  that  it  should  be  arranged  for  correct- 
ing the  effect  of  different  thicknesses  of  covering  glass. 
This  is  accomplished  by  a  fine  screw  movement,  which 
brings  the  front  pair  of  lenses  (1,  Fig.  3)  nearer  or  further 
from  the  object.  In  this  way  the  most  distinct  and  accu- 
rate view  of  an  object  may  be  obtained. 


26  THE    MICROSCOPIST. 

Eyepieces. — The  eye-piece  usually  employed  is  the  Huy- 
genian,  or  negative  eye-piece  (Fig.  4).  This  is  composed 
of  two  plano-convex  lenses,  with  their  plane  sides  next 
the  eye.  Their  focal  lengths  are  as  1  to  3,  and  their 
distance  apart  half  the  sum  of  their  focal  distances. 
Several  of  these,  having  different  magnifying  powers,  are 
supplied  with  good  microscopes.  It  is  best  to  use  a  weak 
eye-piece,  increasing  the  power  of  the  instrument  by 
stronger  objectives  when  necessary.  Kellner's  eye-piece 
has  the  lens  next  the  eye  made  achromatic.  The  peri- 
scopic  eye-piece  of  some  of  the  German  opticians  has  both 
lenses  double  convex.  This  gives  a  larger  field  of  view 
with  some  loss  of  accurate  definition.  For  high  powers, 
I  have  used  a  strong  meniscus  in  place  of  the  lower  lens 
in  the  Huygenian  eye-piece.  Dr.  Royston  Pigott  has 
suggested  improvements  in  eye-pieces  by  using  an  inter- 
mediate Huygenian  combination,  reversed,  between  the 
objective  and  ordinary  eye-piece.  This  gains  power,  but 
somewhat  sacrifices  definition.  Still  better,  he  has  pro- 
posed an  aplanatic  combination,  consisting  of  a  pair  of 
slightly  overcorrected  achromatic  lenses,  mounted  mid- 
way between  a  low  eye-piece  and  the  objective.  This 
has  a  separating  adjustment  so  as  to  traverse  two  or 
three  inches.  The  focal  length  of  the  combination  varies 
from  one  and  a  half  to  three-fourths  of  an  inch.  The 
future  improvement  of  the  microscope  must  be  looked  for 
in  this  direction,  since  opticians  seem  to  have  approached 
the  limit  of  perfection  in  high  power  objectives,  some  of 
which  have  been  made  equivalent  to  g'gth  or  T^th  of  an 
inch  focal  length.  As  an  amplifier,  I  have  used  a  double 
concave  lens  of  an  inch  in  diameter  and  a  virtual  focus  of 
one  and  a  half  inches  between  the  object-glass  and  the 
eye-piece.  If  the  object-glass  be  a  good  one,  this  will 
permit  the  use  of  a  very  strong  eye-piece  with  little  loss 
of  defining  power,  and  greatly  increase  the  apparent  size 
of  the  object. 


THE    MICROSCOPE.  27 

Meclianiml  Arrangements.  —  The  German  and  French 
opticians  devote  their  attention  chiefly  to  the  excellence 
of  their  glasses,  while  the  mechanical  part  of  their  instru- 
ments is  quite  simple,  not  to  say  clumsy.  They  seem  to 
proceed  on  the  principle  that  as  little  as  possible  should  be 
done  by  mechanism,  which  may  be  performed  by  the  hand. 
It  is  different  with  English  and  American  makers,  some 
of  whose  instruments  are  the  very  perfection  of  mechan- 
ical skill.  The  disparity  in  cost,  however,  for  instruments 
of  equal  optical  power  is  quite  considerable. 

Certain  mechanical  contrivances  are  essential  to  every 
good  instrument.  The  German  and  French  stands  are 
usually  vertical,  but  it  is  an  advantage  to  have  one  which 
can  be  inclined  in  any  position  from  vertical  to  horizontal. 
There  should  be  steady  and  accurate,  coarse  and  fine  ad- 
justments for  focussing  ;  a  large  and  firm  stage  with  ledge, 
etc.,  and  with  traversing  motions,  so  as  to  follow  an  object 
quickly,  or  readily  bring  it  into  the  field  of  view  ;  also  a 
concave  and  plane  mirror  with  universal  joints,  capable 
of  being  brought  nearer  or  farther  from  the  stage,  or  of 
being  turned  aside  for  oblique  illumination.  Steadiness, 
or  freedom  from  vibration,  is  of  the  utmost  importance  in 
the  construction,  since  every  unequal  vibration  will  be 
magnified  by  the  optical  power  of  the  instrument. 

Among  so  man}7  excellent  opticians  it  would  be  impos- 
sible to  give  a  complete  list  of  names  whose  workmanship 
is  wholly  reliable,  yet  among  the  foremost  may  be  men- 
tioned Tolles,  of  Boston ;  Wales,  of  Fort  Lee,  ST.  J. ;  Gru- 
now,  of  New  York  ;  and  Zentmayer,  of  Philadelphia  ; 
Powell  &  Leland,  Ross  and  Smith,  Beck  &  Beck,  of  London  ; 
Hartnack  and  Cachet,  of  Paris ;  Merz,  of  Munich  ;  and 
Gundlach,  of  Berlin.  The  optical  performance  of  lenses 
from  these  establishments  is  first  class,  and  the  mechanical 
work  of  their  various  models  good.  The  finest  instru- 
ments from  these  makers,  with  complete  appliances,  are 
quite  costly,  except  the  Germans  and  French,  whose  ar- 


W  THE    MICROSOOPIST. 

rangements,  as  we  have  said,  are  more  simple.  Cheaper 
instruments,  however,  are  made  by  English  and  American 
opticians,  some  of  which  are  very  fine. 

Opticians  divide  microscopes  into  various  classes,  ac- 
cording to  the  perfection  of  their  workmanship  or  the 
accessories  supplied.  The  best  first-class  instruments  have 


FIG.  5. 


Wenham's  Prism  for  the  Binocular  Microscope. 

a  great  variety  of  objectives  and  eye-glasses,  mechanical 
stage  with  rack-work ;  a  sub-stage  with  rack  for  carrying 
various  illuminators  :  a  stand  of  most  solid  construction  ; 
and  every  variety  of  apparatus  to  suit  the  want  or  wish 
of  the  observer.  They  are  great  luxuries,  although  not 
essential  to  perfect  microscopic  work.  The  second  class, 
or  students'  microscopes,  have  less  expensive  stands,  but 
equal  optical  powers,  with  first-class  instruments.  The 


FIG.  6. 


Collins's  Harley  Binocular  Microscope. 


30  THE    MICROSCOPIST. 

third  or  fourth  classes  of  instruments  are  intended  for 
popular  and  educational  use,  and  are  fitted  not  only  with 
stands  of  more  simple  workmanship,  but  with  cheaper 
lenses,  although  often  very  good.  Some  French  achro- 
matic objectives,  adapted  to  this  class,  are  suitable  for  all 
but  the  very  finest  work. 

Binocular  Microscopes. — The  principle  of  the  stereoscope 
has  been  applied  to  the  microscope,  so  as  to  permit  the 
use  of  both  eyes.  The  use  of  such  an  instrument  with 
low  or  medium  powers  is  very  satisfactory,  but  is  less 
available  with  objectives  stronger  than  one-half  inch  focus. 
There  are  two  ways  of  accomplishing  a  stereoscopic  effect 
in  the  microscope.  The  first  and  most  common  is  by 
means  of  Wenham's  prism  (Fig.  5),  placed  above  the  ob- 
jective, and  made  to  slide  so  as  to  transform  the  binocular 
into  a  monocular  microscope. 

The  second  mode  is  to  place  an  arrangement  of  prisms 
in  the  eye-piece,  so  as  to  refract  one-half  the  image  to  the 
right  and  the  other  half  to  the  left,  which  are  viewed  by 
the  corresponding  eyes.  In  either  construction  there  is  a 
provision  made  for  the  variable  distance  between  the  eyes 
of  different  observers.  In  the  frontispiece  is  a  representa- 
tion of  Zentmayer's  grand  American  microscope,  which 
will  afford  a  good  idea  of  the  external  appearance  of  a 
first-class  binocular  microscope.  Students'  and  third-class 
microscopes,  as  before  said,  are  less  complicated  and  of 
more  moderate  cost.  The  mechanical  and  optical  per- 
formance of  Zentmayer's  large  instrument  leaves  scarcely 
anything  to  be  desired.  Instead  of  the  more  expensive 
rack-work  stage,  a  simple  form,  originally  invented  by  Dr. 
Keen,  of  Philadelphia,  and  copied  by  Nachet  and  others, 
is  often  employed.  It  consists  of  a  rotating  glass  disk,  to 
which  is  attached  a  spring,  or  a  V-shaped  pair  of  springs, 
armed  with  ivory  knobs,  which  press  upon  a  glass  plate 
in  the  object-carrier.  The  motion  is  exceedingly  smooth 
and  effective. 


FIG.  8. 


Beck's  Large  Compound  Microscope. 

Fio.  9. 


Hartnack's  Small  Model  Microscope. 


Nachet's  Inverted  Microscope. 


32  THE    MICROSCOPIST. 

Fig.  6  shows  Collins's  Harley  binocular  microscope,  a 
good  second  class  instrument. 

Fig.  7  represents  Beck's  large  compound  miscroscope 
(monocular) ;  and  Fig.  8,  Hartnack's  small  model  micro- 
scope, with  the  body  made  to  incline. 

Fig.  9,  Cachet's  inverted  microscope,  invented  by  Dr. 
Lawrence  Smith  for  chemical  investigations. 


CHAPTER    III. 

MICROSCOPIC    ACCESSORIES. 

IN  addition  to  the  object-glasses,  eye-glasses,  mirror, 
and  mechanical  arrangement  of  the  microscope,  to  which 
reference  was  made  in  the  last  chapter,  several  accessory 
instruments  will  be  useful  and  even  necessary  for  certain 
investigations. 

The.  Diaphragm,  for  cutting  off  extraneous  light  when 
viewing  transparent  objects,  is  generally  needed.  In  some 
German  instruments  it  consists  of  a  cylinder  or  tube,  whose 
upper  end  is  fitted  with  a  series  of  disks  having  central 
openings  of  different  sizes.  The  disk  can  be  adjusted  to 
variable  distances  from  the  object  on  the  stage  so  as  to 
vary  its  effects.  English  and  American  opticians  prefer 
the  rotary  diaphragm,  which  is  of  circular  form,  perforated 
with  holes  of  different  sizes,  and  made  to  revolve  under 
the  stage.  The  gradual  reduction  of  light  can  be  accom- 
plished by  the  cylinder  diaphragm,  since  when  it  is  pushed 
up  so  as  to  be  near  the  stage  it  cuts  off'  only  a  small  part 
of  the  cone  of  rays  sent  upwards  by  the  concave  mirror, 
but,  when  drawn  downwards,  it  cuts  off  more. 

Collins's  Graduating  Diaphragm,  which  is  made  with 
four  shutters,  moving  simultaneously  by  acting  on  a  lever 


MICROSCOPIC    ACCESSORIES. 


33 


handle,  so  as  to  narrow  the  aperture,  accomplishes  the 
end  most  perfectly.     (Fig  10.) 


Collins's  New  (jr.  dilating  Diaphragm. 

Beck's  Iris  Diaphragm  is  a  further  improvement  of  this 
sort. 

Condensers. — The  loss  of  light  resulting  from  the  em- 
ployment of  high  powers  has  led  to  several  plans  for  con- 
densing light  upon  the  object.  Sometimes  a  plano-convex 
lens,  or  combination  of  lenses,  is  made  to  slide  up  and 
down  under  the  stage.  A  Kellner's  eyepiece,  or  some 

FIG.  11. 


Smith  and  Beck's  Achromatic  Condenser. 

similar  arrangement,  especially  if  fitted  with  a  special 
diaphragm,  containing  slits  and  holes,  some  of  the  latter 
having  central  stops,  is  of  very  great  use.  First-class  in- 
struments are  fitted  up  with  achromatic  condensers  (Fig. 
11),  carrying  revolving  diaphragms,  some  of  whose  aper- 

3 


34  THE    MICROSCOPIST. 

tures  are  more  or  less  occupied  by  stops,  or  solid  disks,  so 
as  to  leave  but  a  ring  of  space  for  light  to  pass  through. 
The  effect  of  these  annular  diaphragms  is  similar  to  an 
apparatus  for  oblique  illumination. 

The  Webster  condenser  is  similar  in  its  optical  parts  to 
the  Kellner  eye-piece,  and  is  provided  with  a  diaphragm 
plate,  with  stops  for  oblique  illumination,  as  well  as  a 


Webster's  Condenser,  with  Graduating  Diaphragms. 

graduating  diaphragm  for  the  regulation  of  the  central 
aperture.     This  is  a  most  useful  accessory.     (Fig.  12.) 

Oblique  Illuminators  — Certain  fine  markings  on  trans- 
parent objects  can  scarcely  be  made  out  by  central  illumi- 
nation, but  require  the  rays  to  come  from  one  side,  so  as 
to  throw  a  shadow.  Sometimes  this  is  well  accomplished 
by  turning  the  mirror  aside  from  the  axis  of  the  micro- 
scope, and  sometimes  by  the  use  of  one  of  the  condensers 
referred  to  above.  Amici's  prism,  which  has  both  plane 
and  lenticular  surfaces,  is  sometimes  used  on  one  side  and 
under  the  stage,  in  lieu  of  the  mirror.  For  obtaining 
very  oblique  pencils  of  light  the  double  hemispherical  con- 
denser of  Mr.  Reade  has  been  invented.  It  is  a  hemi- 
spherical lens  of  about  one  and  a  half  inch  diameter,  with 
its  flat  side  next  the  object,  surmounted  by  a  smaller  lens 
of  the  same  form,  the  flat  side  of  which  is  covered  with  a 
thin  diaphragm,  having  an  aperture  or  apertures  close  to 


MICROSCOPIC  ACCESSORIES. 


35 


its  margin.  These  apertures  may  be  V-shaped,  extending 
to  about  a  quarter  of  an  inch  from  the  centre. 

If  the  microscope  has  a  mechanical  stage,  with  rack- 
work,  or  is  otherwise  too  thick  to  permit  the  mirror  to 
be  turned  aside  for  very  oblique  illumination,  Nachet's 
prism  will  prove  of  service.  I  have  also  contrived  a  useful 
oblique  illuminator  for  this  purpose,  by  cementing  with 
Dammar  varnish  a  plano-convex  lens  on  one  face  of  a  to- 
tally-reflecting prism,  and  near  the  upper  edge  of  the 
other  side  (at  90°)  an  achromatic  lens  from  a  French  trip- 
let. The  prism  is  made  to  turn  on  a  hinge,  so  that  an 
accurate  pencil  of  light  may  fall  on  the  object  at  any 
angle  desired. 

Dark-ground  Illuminators. — Some  beautiful  effects  are 
produced,  and  the  demonstration  of  some  structures  aided, 
by  preventing  the  light  condensed  upon  the  object  from 
entering  the  object-glass.  In  this  way  the  object  appears 


FIG.  13. 


FIG.  14. 


Nobert's  Illuminator. 


Parabolic  Illuminator. 


self-luminous  on  a  black  ground.  For  low  powers  this 
can  be  easily  done  by  turning  aside  the  concave  mirror  as 
in  oblique  illumination,  or  by  employing  Noberfs  illumi- 
nator, which  is  a  thick  plano-convex  lens,  in  the  convex 


36 


THE    MICROSCOPIST. 


surface  of  which  a  deep  concavity  is  made.  The  plane 
side  is  next  the  object.  This  throws  an  oblique  light  all 
round  the  object.  A  substitute  for  this,  called  a  spot  lens, 
is  often  used,  and  differs  only  from  Robert's  in  having  a 
central  black  stop  on  the  plane  side  instead  of  a  concavity 
(Fig.  13).  A  still  greater  degree  of  obliquity  suitable  for 
high  powers  must  be  sought  by  the  use  of  the  parabolic 
illuminator  (Fig.  14).  This  is  usually  a  paraboloid  of  glass, 
which  reflects  to  a  focus  the  rays  which  fall  upon  its  inter- 
nal surface,  while  the  central  rays  are  stopped. 

Illuminators  for  Opaque  Objects. — Ordinary  daylight  is 
hardly  sufficient  for  the  illumination  of  opaque  objects, 


FIG.  15. 


Bull's-eye  Condenser. 


so  that  microscopists  resort  to  concentrated  lamplight,  etc. 
Gas,  paraffine,  and  camphene  lamps,  have  been  variously 
modified  for  this  purpose,  but  few  are  better  than  the  Ger- 


MICROSCOPIC  ACCESSORIES.  37 

man  student's  Argand  lamp  for  petroleum  or  kerosene 
oil,  as  it  is  called.  To  concentrate  the  light  from  such  a 
source  a  condensing  lens  is  used,  either  attached  to  the 
microscope  or  mounted  on  a  separate  stand.  Sometimes 
a  bull's-eye  condenser  is  used  for  more  effective  illumination 
(Fig.  15).  This  is  a  large  plano-convex  lens  of  short  focus, 
mounted  on  a  stand.  For  such  a  lens  the  position  of  least 
spherical  aberration  is  when  its  convex  side  is  towards 
parallel  rays ;  hence,  in  daylight,  the  plane  side  should  be 
next  the  object.  But,  if  it  is  desired  to  render  the  diverg- 


FIG.  16. 


Parabolic  Speculum. 

ing  rays  of  a  lamp  parallel,  the  plane  side  should  be  next 
the  lamp,  and  rather  close  to  it.  The  use  of  this  con- 
denser will  also  commend  itself,  when  used  as  last  referred 
to,  in  microscopic  dissection.  It  will  throw  a  bright  light 
from  the  lamp  directly  on  the  trough,  watch-glass,  etc.,  in 
which  the  specimen  is  being  prepared.  The  Lieberkuhn, 
or  a  concave  speculum  attached  to  the  object-glass,  and 
reflecting  the  light  from  the  mirror  directly  upon  the 
object,  is  one  of  the  oldest  contrivances  for  the  illumina- 
tion of  opaque  objects ;  but  the  most  convenient  instru- 
ment is  the  parabolic  speculum  (Fig.  16),  a  side  mirror  with 


38  THE    MICROSCOPIST. 

a  parabolic  surface  attached  to  the  objective.  For 
powers,  a  lateral  aperture  above  the  objective  has  been 
made  to  throw  the  light  down  through  the  object-glass 
itself  by  means  of  a  small  reflector,  as  devised  by  Prof. 
Smith,  or  a  disk  of  thin  glass,  as  in  Beck's  vertical  illumi- 
nator. This  latter  is  attached  to  an  adapter  interposed 
between  the  objective  and  the  body  of  the  microscope. 

Instruments  for  Measuring  and  Drawing  Objects. — Screw 
micrometers  are  sometimes  used  with  the  microscope,  as 
with  the  telescope,  for  the  measurement  of  objects ;  but 
the  less  expensive  and  simpler  glass  micrometers  have 
generally  superseded  them.  The  latter  are  of  two  sorts, 
the  stage  and  the  ocular  micrometer.  The  stage  micrometer 
is  simply  a  glass  slide,  containing  fine  subdivisions  of  the 
inch,  line,  etc.,  engraved  by  means  of  a  diamond  point. 
Jn  case  the  rulings  are  TJi)ths  and  f  ^ths  of  an  inch,  it 
is  evident  that  an  object  may  be  measured  by  comparison 
with  the  divisions  ;  yet,  in  practice,  it  is  found  incon- 
venient to  use  an  object  with  the  stage  micrometer  in  this 
way,  and  it  will  be  found  better  to  combine  its  use  with 
that  of  the  drawing  apparatus,  as  hereafter  described. 
The  ocular,  or  eye-piece  micrometer,  is  a  ruled  slip  of  glass 
in  the  eye-piece.  Its  value  is  a  relative  one,  depending  on 
the  power  of  the  objective  and  the  length  of  the  micro- 
scope tube.  By  comparing  the  divisions  with  those  of  the 
stage  micrometer  their  value  can  be  readily  ascertained. 
Thus,  if  five  spaces  of  the  eye-piece  micrometer  cover  one 
space  of  the  stage  micrometer,  measuring  T01(JIJth  of  an 
inch,  their  value  will  be  ^J^th  of  an  inch  each. 

Different  standards  of  measurement  are  used  in  different 
countries.  English  and  American  microscopists  use  the 
inch.  In  France,  and  generally  in  Germany,  the  Paris 
line  or  the  millimetre  is  used.  The  millimetre  is  0.4433  of 
a  Paris  line  and  0.4724  of  an  English  line  ( ,!2th  of  an 
inch). 

In  the  French  system  the  fundamental  unit  is  the  metre, 


MICROSCOPIC    ACCESSORIES. 


39 


which  is  the  ten-millionth  part  of  the  quadrant  of  the 
meridian  of  Paris.  The  multiples  are  made  by  prefixing 
Greek  names  of  numbers,  and  the  subdivisions  by  prefix- 
ing Latin  names.  Thus,  for  decimal  multiples,  we  have 
deco,  hecto,  kilo,  and  myrio  ;  and,  for  decimal  subdivisions, 
deci,  centi,  and  milli.  The  following  may  serve  for  con- 
verting subdivisions  of  the  metre  into  English  equiva- 
lents : 

A  millimetre  equals  0.03937  English  inches. 

A  centimetre      "       0.39371  " 

A  decimetre        "       3.93708  " 

One  inch  =  2.539954  centimetres,  or  25.39954  millimetres. 

'For  drawing  microscopic  objects  the  camera  lucida  will 
be  found  useful.  This  is  a  small  glass  prism  attached  to 
the  eye-piece.  The  microscope  is  inclined  horizontally, 

FIG.  17. 


Oberhauser's  Drawing  Apparatus. 

and  the  observer,  looking  into  the  prism,  sees  the  object 
directly  under  his  eye,  so  that  its  outlines  may  be  drawn 
on  a  piece  of  paper  placed  on  the  table.  Some  practice, 
however,  is  needed  for  satisfactory  results.  For  the  up- 
right stands  of  German  and  French  microscopes,  the  camera 
lucida  of  Chevalier  &  Oberhauser  is  available.  This  is  a 
prism  in  a  rectangular  tube,  in  front  of  which  is  the  eye- 
piece, carrying  a  small  glass  prism  (c,  Fig.  17),  surrounded 


40  THE    MICROSCOPIST. 

by  a  black  metal  ring.  'A  paper  placed  beneath  is  visible 
through  the  opening  in  the  ring,  and  the  image  reflected 
by  the  prism  upon  it  can  be  traced  by  a  pencil.  It  is  neces- 
sary to  regulate  the  light  so  that  the  point  of  the  pencil 
may  be  seen. 

Dr.  Beale  has  recommended,  in  lieu  of  the  camera  lucida, 
a  piece  of  slightly  tinted  plate  glass  (Fig.  18),  placed  in  a 
short  tube  over  the  eye-piece  at  an  angle  of  45°.  This  is 
a  cheap  and  effective  plan.  A  similar  purpose  is  served 


Fio.  19. 


Beale's  Tint-glass  Camera.  Sceminering's  Steel  Disk. 

by  a  little  steel  disk,  smaller  than  the  pupil  of  the  eye, 
placed  at  the  same  angle  (Fig.  19). 

The  most  simple  method  of  measuring  objects  is  to 
employ  one  of  the  above  drawing  instruments,  placing 
first  on  the  microscope  stage  an  ordinary  micrometer,  and 
tracing  its  lines  on  the  paper.  Then  the  outline  of  the 
object  can  be  traced  and  compared  with  the  lines.  The 
magnifying  power  of  an  object-glass  can  also  be  readily 
found  by  throwing  the  image  of  the  lines  in  a  stage 
micrometer  upon  a  rule  held  ten  inches  below  the  eye- 
piece, looking  at  the  magnified  image  with  one  eye  and 
at  the  rule  with  the  other.  Dr.  Beale  strongly  urges 
observers  to  delineate  their  own  work  on  wood  or  stone, 
since  they  can  do  it  more  exactly  and  truthfully  than  the 


MICROSCOPIC    ACCESSORIES.  41 

most  skilled  artists  who  are  unfamiliar  with  microscopic 
manipulation. 

Other  accessory  apparatus,  such  as  a  frog-plate,  for  more 
readily  observing  the  circulation  in  a  frog's  foot ;  an 
animalcule  cage,  or  live  box ;  a  compressorium,  for  apply- 
ing pressure  to  an  object ;  fishing  tubes ;  watch-glasses  ; 
growing-slides,  etc.,  will  commend  themselves  on  personal 
inspection. 

For  preventing  the  evaporation  of  fluids  during  obser- 
vation, Recklinghausen  invented  the  moist  chamber  (Fig. 
20),  consisting  of  a  glass  ring  on  a  slide,  to  which  is  fas- 
tened a  tube  of  thin  rubber,  the  upper  end  of  which  is 
fastened  round  the  microscope  tube  with  a  rubber  band. 


FIG.  20. 


JLiecklJiJgluuisen's  Moist  (.  dumber. 


A  simpler  form  of  moist  chamber  may  be  made  by  a 
glass  ring  cemented  on  a  slide.  A  few  drops  of  water 
cautiously  put  on  the  inner  edge  of  the  ring  with  a  brush, 
or  a  little  moist  blotting-paper  may  be  placed  inside.  The 
object  (as  a  drop  of  frog's  blood,  etc.)  may  then  be  put  on 
a  circular  thin  cover,  which  is  placed  inverted  on  the  ring. 
A  small  drop  of  oil  round  the  edge  of  the  cover  keeps  it 
air  and  water-tight- 
Somewhat  similar  to  the  above  is  Strieker's  gas  chamber 
(Fig.  21).  On  the  object-slide  is  a  ring  of  glass,  or  putty, 
with  its  thin  cover.  Through  this  ring  two  glass  tubes 
are  cemented,  one  of  which  is  connected  with  a  rubber 


42 


THE    MICROSCOPIST. 


tube  for  the  entrance  of  gas,  while  the  other  serves  for 
its  exit. 

For  the  study  of  phenomena  in  the  fluids,  etc.,  of  warm- 
blooded animals,  we  need,  in  addition  to  the  moist  cham- 
ber, some  way  of  keeping  the  object  warm.  This  may  be 
roughly  done  by  a  perforated  tin  or  brass  plate  on  the 
stage,  one  end  of  which  is  warmed  by  a  spirit-lamp.  A 
piece  of  cocoa  butter  or  wax  will  show  by  its  melting 
when  the  heat  is  sufficient.  Schultze's  warm  stage  is  a 
more  satisfactory  and  scientific  instrument.  It  is  a  brass 
plate  to  fit  on  the  stage,  perforated  for  illumination,  and 
connected  with  a  spirit-lamp  and  thermometer,  so  that 


FIG.  21. 


Strieker's  Gas  Chamber. 


the  amount  of  heat  may  be  exactly  regulated.  Other 
arrangements  have  been  proposed  to  admit  a  current  of 
warm  water,  or  for  the  passage  of  electricity  through  an 
object  while  under  observation,  which  are  scarcely  neces- 
sary to  describe. 

The  Polariscope. — The  nature  and  properties  of  polarized 
light  belong  rather  to  a  treatise  on  optics  or  natural  phi- 
losophy than  to  a  work  like  the  present,  yet  a  very  brief 
account  may  not  be  out  of  place.  We  premise,  then,  that 
every  ray  or  beam  of  common  light  is  supposed  to  have 
at  least  two  sets  of  vibrations,  vertical  and  horizontal. 
As  these  vibrations  have  different  properties,  the  ray  when 


MICROSCOPIC    ACCESSORIES. 


43 


divided  is  said  to  be  polarized,  from  a  fancied  resemblance 
to  the  poles  of  a  magnet.  The  division  of  the  vibrations 
may  be  effected  (i.  <?.,  the  light  may  be  polarized)  in  vari- 
ous ways.  For  the  microscope  the  polarizer  is  a  Nichol's 
prism,  composed  of  a  crystal  of  Iceland  spar,  which  has 
been  divided  and  again  cemented  with  Canada  balsam,  so 
as  to  throw  one  of  the  doubly  refracted  rays  aside  from 
the  field  of  view  (Fig.  22).  Such  a  prism  is  mounted  in 
a  short  tube  and  attached  to  the  under  side  of  the  stage. 
In  order  to  distinguish  the  effects  of  polarized  light,  an 
analyzer  is  also  needed.  This  usually  consists  of  another 


FIG.  22. 


FIG.  23. 


Nichol's  Prism. 


Polarizer  and  Analyzer. 


similar  NichoPs  prism,  attached  either  to  the  eye-piece  or 
just  above  the  objective.  The  latter  position  gives  a 
larger  field,  but  the  former  better  definition.  Fie;.  23 
shows  the  polarizer  and  the  analyzer.  The  polarizer  is 
improved  by  the  addition  of  a  convex  lens  next  the  object. 
Hartnack  has  also  improved  the  eye-piece  analyzer  by 
adding  a  graduated  disk  and  vernier. 

When  the  polarizer  and  analyzer  have  been  put  in  place, 
they  should  be  rotated  until  their  polarizing  planes  are 
parallel,  and  the  mirror  adjusted  so  as  to  give  the  most 
intense  light.  If  now  the  polarizing  planes  are  placed  at 
right  angles,  by  turning  one  of  them  90°,  the  field  is  ren- 


44 


THE    MICROSCOPIST. 


dered  dark,  and  doubly  refracting  bodies  on  the  stage  of 
the  microscope  appear  either  illuminated  or  in  colors.  If 
a  polarized  ray  passes  through  a  doubly  refracting  film, 
as  of  selenite,  it  forms  two  distinct  rays,  the  ordinary 
and  the  extraordinary  ray.  Each  of  these  will  be  of  dif- 
ferent colors,  according  to  the  thickness  of  the  film.  If 
one  be  red,  the  other  will  be  green,  these  colors  being 
complementary.  By  using  the  analyzer  one  of  these  rays 
is  alternately  suppressed,  so  that  on  revolving  the  appa- 
ratus the  green  and  red  rays  appear  to  alternate  at  each 
quarter  of  a  circle.  Films  of  selenite  are  often  mounted 
so  as  to  revolve  between  the  polarizer  and  the  stage. 
Darker's  selenite  stage  is  sometimes  used  for  this  purpose 
(Fig.  24).  With  such  a  stage  a  set  of  selenites  is  usually 


Fio.  24. 


Darker's  Selenite  Stage. 

supplied,  giving  the  blue,  purple,  and  red,  with  their  com- 
plementary colors,  orange,  yellow,  and  green.  By  this 
combination  all  the  colors  of  the  spectrum  may  be  ob- 
tained. The  selenite  disks  generally  have  engraved  on 
them  the  amount  of  retardation  of  the  undulations  of 
white  light,  thus:  J,  },  and  J.  If  these  are  placed  so 
that  their  positive  axes  (marked  PA)  coincide,  they  give 
the  sum  of  their  combined  retardations. 

The  Microspectroscope.— Ordinary  spectrum  analysis,  by 
determining  the  number  and  position  of  certain  narrow 
lines  in  the  spectra  of  luminous  bodies,  called  Fraunhofer's 


MICROSCOPIC  ACCESSORIES. 


45 


lines,  enables  the  chemist  to  identify  different  substances. 
The  object  of  the  microspectroscope  is  different.  It  en- 
ables us  to  distinguish  substances  by  the  absence  of  cer- 
tain rays  in  the  spectrum,  or,  in  other  words,  to  judge  of 
substances  by  a  scientific  examination  of  their  color.  The 
color  of  a  body  seen  with  the  naked  eye  is  the  general 
impression  made  by  the  transmitted  light,  and  this  may 
be  the  same  although  the  compound  rays  may  differ 


ii 


The  Sorby-Browning  Microspectroscope. 

greatly,  so  that  colors  which  seem  absolutely  alike  may 
be  distinguished  by  their  spectra.  Many  solutions  are 
seen  to  absorb  different  colors  in  very  definite  parts  of  the 
spectrum,  forming  absorption  bands  or  lines,  varying  in 
width  and  intensity  according  to  the  strength  of  the  so- 
lution. The  instrument  usually  employed  consists  of  a 
direct-vision  spectrum  apparatus  attached  to  the  eye  piece 
of  the  microscope,  which  shows  the  principal  Fraunhofer 


46 


THE    MICROSCOPIST. 


lines  by  daylight,  or  a  spectrum  of  the  light  transmitted 
by  any  object  in  the  field  of  view.  A  reflecting  prism  is 
placed  under  one-half  of  the  slit  of  the  apparatus  so  as  to 
transmit  from  a  side  aperture  a  standard  spectrum  for 
comparison.  In  Fig.  25,  A  is  a  brass  tube  carrying  the 
compound  direct-vision  system  of  five  prisms  and  an 
achromatic  lens.  This  tube  is  moved  by  the  milled  head 


Fre.  2G. 


Spectroscope  with  Micrometer. 

B,  so  as  to  bring  to  a  focus  the  different  parts  of  the 
spectrum.  This  is  important  when  the  bands  or  lines  to 
be  examined  are  delicate.  D  is  the  stage  on  which  objects 
for  comparison  are  placed.  The  light  passing  through 
them  from  the  mirror  i,  goes  through  a  side  opening  to  a 
reflecting  prism  which  covers  a  part  of  a  slit  in  the  bot- 
tom of  the  tube  A.  This  slit  is  opened  and  shut  by  means 
of  the  screws  c  and  H.  Fig.  26  shows  the  internal  ar- 


MICROSCOPIC    ACCESSORIES.  47 

rangement  of  the  prisms  and  lens,  together  with  a  microm- 
eter for  measuring  the  position  of  lines  or  absorption 
bands.  To  use  the  microspectroscope,  remove  the  tube 
A,  with  the  prisms,  and  insert  the  tube  G  in  the  place  of 
the  eye-piece  of  the  microscope.  With  the  lowest  power 
object-glass  which  is  suitable,  and  the  slit  opened  wide  by 
the  screw  H,  the  object  on  the  stage  of  the  microscope, 
illuminated  by  the  mirror  or  condenser,  is  brought  to  a 
focus,  the  tube  A  replaced  and  adjusted  for  focus  by  the 
screw  B,  while  the  slit  is  regulated  by  c  and  H  until  a  well- 
defined  spectrum  is  seen.  To  determine  the  position  of 
the  absorption  lines,  remove  the  upper  cover  of  the  tube 
A  and  replace  it  with  that  carrying  the  micrometer  repre- 
sented in  Fig.  26.  The  mirror  illuminates  a  transparent 
line  or  cross,  whose  image  is  refracted  by  a  lens  c,  mov- 
able by  a  screw  B,  and  reflected  at  an  angle  of  45°  from 
the  upper  surface  of  the  prisms,  so  as  to  be  seen  upon  the 
spectrum.  By  means  of  the  micrometer  screw  M,  this  is 
made  to  move  across  the  spectrum,  so  that  the  distance 
between  the  lines  may  be  determined.  In  order  to  com- 
pare the  results  given  by  different  instruments,  the 
observer  should  measure  the  position  of  the  principal 
Fraunhofer  lines  in  bright  daylight,  and  mark  them  on 
a  cardboard  scale,  which  may  be  preserved  for  reference. 
By  comparing  the  micrometric  measurement  of  lines  in 
the  spectrum  of  any  substance  observed  by  artificial  light 
with  such  a  scale,  their  position  may  readily  be  seen. 

In  using  the  microspectroscope  some  objects  require  a 
diaphragm  of  small  size,  and  others,  especially  with  the 
1J  or  2-inch  objective,  a  cap  with  a  hole  ,'gth  of  an  inch 
in  diameter  over  the  end  of  the  microscope,  to  prevent 
extraneous  light  from  passing  through  the  tube. 

Nose-piece. — For  the  purpose  of  facilitating  observations 
with  objectives  of  different  powers  a  revolving  nose-piece 
has  been  contrived,  carrying  two,  three,  or  four  objectives, 


48  THE    MICROSCOPIST 

which  may  he  brought  quickly  into  the  axis  of  the  instru- 
ment. 

Object-finders. — It  is  sometimes  tedious  to  find  a  small 
object  on  a  slide,  particularly  with  high  powers,  and  a 
number  of  contrivances,  as  Maltwood's  finder,  have  been 
proposed  for  this  end.  A  very  simple  method,  however, 
may  serve.  Mark  on  the  stage  two  crosses,  one  like  the 
sign  of  addition  -}-,  and  the  other  like  the  sign  of  multi- 
plication x  ,  and,  when  the  object  is  found,  mark  the  slide 
to  correspond  with  the  marks  below.  If  the  stage  be  a 
mechanical  one  it  will  be  necessary  to  arrange  it  in  the 
previous  position. 

Microscopic  Photography. — Many  European  experimen- 
ters have  succeeded  in  taking  microscopic  photographs, 
but  a  great  advance  in  this  direction  has  been  made  under 
the  direction  of  the  medical  department  of  the  United 
States  army  at  Washington.  Lieutenant-Colonel  Wood- 
ward has  succeeded  in  furnishing  permanent  records  of 
many  details  of  structure,  which  exhibit  the  very  perfec- 
tion of  art.  In  a  work  like  the  present  a  full  account  of 
the  apparatus  and  methods  employed  would  be  out  of  place. 
Dr.  Beale's  How  to  Work  with  the  Microscope,  and  the  re- 
ports issued  from  the  Surgeon-General's  office  at  Wash- 
ington, will  give  the  details. 


CHAPTER    IV. 

USE   OF   THE   MICROSCOPE. 

Care  of  the  Instrument. — But  little  satisfaction  will  be 
secured  in  microscopic  work  for  any  length  of  time  with- 
out scrupulous  care  of  the  lenses,  etc.,  belonging  to  the 
instrument,  and  habits  of  this  kind  should  be  early  ac- 
quired. When  in  frequent  use  the  microscope  should  be 


USE    OF    THE    MICROSCOPE.  49 

seldom  packed  away  in  its  case,  as  a  certain  necessary 
stiffness  of  motion  in  its  various  parts  might  thereby  be 
lessened.  Yet  it  should  be  kept  free  from  dust  and  damp. 
A  bell-s;lass  cover,  or  glass  case,  or  a  cabinet  which  will 
admit  the  reception  of  the  instrument  in  a  form  ready  for 
immediate  use,  is  desirable.  Before  using,  the  condition 
of  objective  and  eye-piece  should  be  examined  as  well  as 
of  the  mirror,  and  dust  or  dampness  removed.  Another 
examination  should  be  made  before  the  microscope  is  put 
away. 

Stains  on  the  brass-work  may  be  removed  by  a  linen 
rag,  and  dust  on  the  mirror  and  lenses  by  a  fine  camel's- 
hair  brush,  or  very  soft  and  clean  chamois  skin.  Frequent 
wiping  will  injure  the  polish  of  the  lenses. 

The  upper  surfaces  of  the  lenses  in  the  eye-pieces  and 
the  mirror  will  need  the  most  frequent  attention  The 
objectives,  if  carefully  handled  and  kept  in  their  boxes 
when  not  in  use,  will  seldom  require  cleaning.  If  the  front 
of  the  objective  becomes  accidentally  wet  with  fluid  it 
should  be  at  once  removed,  and,  when  reagents  are  used, 
great  care  should  be  taken  to  prevent  contact  with  the 
front  of  the  lens. 

Care  of  the  Eyes.— Continuous  observation,  especially  by 
lamplight,  and  with  high  powers,  has  doubtless  a  ten- 
dency to  injure  the  sight.  To  cease  work  as  soon  as 
fatigue  begins  is,  however,  a  simple  but  certain  rule  for 
protection.  This  time  will  vary  greatly,  according  to  the 
general  tone  and  vigor  of  the  observer.  It  is  also  impor- 
tant to  use  the  eyes  alternately  if  a  monocular  instrument 
is  employed,  as  otherwise  great  difference  both  in  the 
focus  and  in  the  sensitiveness  of  the  eyes  will  result.  The 
habit  of  keeping  the  unemployed  eye  open  is  a  good  one, 
and,  though  troublesome  at  first,  is  not  difficult  to  ac- 
quire. It  is  well  to  protect  the  eye  from  all  extraneous 
light,  and  to  exclude  every  part  of  the  object  except  that 
which  is  under  immediate  observation.  The  diaphragm 

4 


50  THE    MICKOSCOPIST. 

will  serve  this  end  as  well  as  modify  the  quality  of  the 
light.  For  very  delicate  observations  a  dark  shade  over 
the  stage,  which  may  be  fastened  by  an  elastic  ring  to 
the  microscope-tube,  so  as  to  shut  off  extraneous  light, 
will  be  useful. 

Table,  etc. — The  microscopist's  work-table  should  be 
large  and  massive,  so  as  to  be  convenient  and  free  from 
vibration.  Drawers  for  accessories  and  materials  used  in 
preparing  and  mounting  objects  are  also  desirable,  as  well 
as  a  few  bell-glasses  for  secluding  objects  from  dust.  Re- 
agents should  always  be  removed  from  the  table  after  use 
and  kept  in  another  place. 

Light. — Dr.  Carpenter  has  well  said,  "  Good  daylight  is 
to  be  preferred  to  any  other  kind  of  light,  but  good  lamp- 
light is  preferable  to  bad  daylight."  A  clear  blue  sky 
gives  light  enough  for  low  powers,  but  a  dull  white 
cloudiness  is  better.  The  direct  rays  of  the  sun  are  too 
strong,  and  should  be  modified  by  a  white  curtain,  reflec- 
tion from  a  surface  of  plaster  of  Paris,  or,  still  better,  by 
passing  through  a  glass  cell  containing  a  solution  of  am- 
monio-sulphate  of  copper. 

Various  kinds  of  lamps  have  been  contrived  for  micro- 
scopic use ;  among  the  best  are  the  German  and  French 
"  student's  reading  lamps,"  which  burn  coal  oil  or  petro- 
leum. It  is  often  useful  to  moderate  such  a  light  by  the 
use  of  a  chimney  of  blue  glass,  or  by  a  screen  of  blue  glass 
between  the  flame  and  the  object.  Dr.  Curtis  contrived 
a  useful  apparatus,  consisting  of  a  short  petroleum  lamp 
placed  in  an  upright,  oblong  box.  On  one  side  of  the  box 
is  an  opening  occupied  with  blue  glass ;  on  another  side 
the  opening  has  ground-glass,  as  well  as  a  piece  colored 
blue,  and  a  plano-convex  lens  so  placed  as  to  condense  the 
light  thus  softened  to  a  suitable  place  on  the  table. 

As  a  general  rule  the  light  should  come  from  the  left 
side,  and  that  position  assumed  or  inclination  given  to  the 
instrument  which  is  most  comfortable  to  the  observer. 


USE    OF    THE    MICROSCOPE.  51 

English  and  American  microscopists  prefer  an  inclined 
microscope,  while  the  German  and  French  instruments 
being  usually  vertical  do  not  permit  this  arrangement. 

Adjustment. — The  details  of  microscopic  adjustments 
are  only  to  be  learned  by  practice,  yet  a  few  directions 
may  be  instructive.  The  selection  of  the  objectives  and 
eye-pieces  depends  on  the  character  of  the  object.  As  a 
general  rule,  the  lowest  powers  which  will  exhibit  an 
object  are  the  best.  It  is  best  to  use  weak  eye-pieces  with 
the  stronger  objectives,  yet  much  depends  on  the  perfec- 
tion of  the  glasses  employed. 

The  focal  adjustment  can  be  made  with  the  coarse  ad- 
justment or  quick  motion  when  low  powers  are  employed ; 
but  for  higher  powers  the  line  adjustment  screw  is  essen- 
tial. Care  must  be  taken  not  to  bring  the  objective  into 
close  or  sudden  contact  with  the  thin  glass  cover  over  the 
object,  and,  in  changing  object-glasses,  the  microscope 
body  should  be  raised  from  the  stage  by  the  coarse  adjust- 
ment. 

•The  actual  distance  between  the  object  and  object-glass 
is  much  less  than  the  nominal  focal  length,  so  that  the 
1  inch  objective  has  a  working  distance  of  about  J  an 
inch,  the  Jth  of  about  ^th  of  an  inch,  while  shorter  ob- 
jectives require  the  object  to  be  covered  with  the  thinnest 


Sometimes,  in  high  powers,  and  especially  with  immer- 
sion-lenses, an  adjustment  of  the  object-glass  is  necessary 
in  order  to  suit  the  thickness  of  the  glass  cover.  With 
thick  covers  the  individual  lenses  must  be  brought  nearer 
to  each  other,  and,  with  very  thin  covers,  moved  farther 
apart. 

If  immersion-objectives  be  employed  a  drop  of  water  is 
placed  on  the  glass  cover  with  a  glass  rod  or  camel's-hair 
pencil,  and  a  second  drop  on  the  lens.  The  lens  and  object 
are  then  approximated  till  the  drops  flow  together  and  the 
focus  is  adjusted.  By  turning  the  ecrew  of  the  objective 


52  THE    MICROSCOPIST. 

and  using  the  fine  adjustment  the  best  position  will  be 
shown  by  the  sharper  and  more  delicate  image  of  the 
object. 

For  other  details  respecting  adjustment  the  reader  is 
referred  to  the  chapter  on  Microscopic  Accessories. 

Errors  of  Interpretation. — True  science  is  hindered  most 
of  all  by  speculation  and  false  philosophy,  which  often 
assume  its  garb  and  name,  but  it  is  also  retarded  by  im- 
perfeet  or  false  observation.  It  is  much  less  easy  to  see 
than  beginners  imagine,  and  still  less  easy  to  know  what 
we  see.  The  latter  sometimes  requires  an  intellect  of  sur- 
passing endowments.  The  sources  of  error  are  numerous, 
but  some  require  special  caution,  and  to  these  we  now 
refer. 

The  nature  of  microscopic  images  causes  error  from 
imperfect  focal  adjustment.  We  see  distinctly  only  that 
stratum  of  an  object  which  lies  directly  in  focus,  and  it  is 
seldom  that  all  parts  of  an  object  can  be  in  focus  together. 
Hence  we  only  recognize  at  once  the  outline  of  an  object, 
but  not  its  thickness,  and,  as  the  parts  which  are  out  of 
focus  are  indistinct,  we  may  readily  fall  into  error.  Glasses 
vary  much  in  this  respect.  Some  have  considerable  pene- 
trating and  defining  power  even  with  moderate  angular 
aperture,  and  are  better  for  general  work  than  those  more 
perfect  instruments  which  give  paler  images  and  only  re- 
veal their  excellencies  to  the  practiced  microscopist. 

Sometimes  the  focal  adjustment  leads  to  error  on  ac- 
count of  the  reversal  of  the  lights  and  shadows  at  differ- 
ent distances.  Thus  the  centres  of  the  biconcave  blood- 
disks  appear  dark  when  in  focus,  and  bright  when  a  little 
within  the  focus ;  while  the  hexagonal  elevations  of  a  dia- 
tom, as  the  Pleurosigma  angulatum,&vs  light  when  in  focus, 
with  dark  partitions,  and  dark  when  just  beyond  the 
focus.  From  this  we  gather  a  means  of  discrimination, 
since  a  convex  body  appears  lighter  by  raising  the  micro- 
scope, and  a  concave  by  lowering  it. 


USE    OP    THE    MICROSCOPE.  53 

The  refractive  power  of  the  object,  or  of  the  medium  in 
which  it  lies,  is  sometimes  a  source  of  error.  Thus  a 
human  hair  was  long  thought  to  be  tubular,  because  of 
the  convergence  of  the  rays  of  light  on  its  cylindrical  con- 
vexity. A  glass  cylinder  in  balsam  appears  like  a  flat 
band,  because  of  the  nearly  equal  refractive  powers  of 
object  and  medium.  The  lacunae  and  canaliculse  of  bone 
were  long  considered  solid,  because  of  the  dark  appear- 
ance presented  on  account  of  the  divergence  of  the  rays 
passing  through  them.  Their  penetration  with  Canada 
balsam,  however,  proves  them  to  be  cavities.  Air-bubbles, 
from  refraction,  present  dark  rings,  and,  if  present  in  a 
specimen,  seldom  fail  to  attract  the  first  attention  of  an 
inexperienced  observer.  The  difference  between  oil-globules 
in  water  and  water  in  oil,  or  air-bubbles,  should  be  early 
learned,  as  in  some  organized  structures  oil-particles  and 
vacuoles  (or  void  spaces)  are  often  interspersed.  A  globule 
of  oil  in  water  becomes  darker  as  the  object-glass  is  de- 
pressed, and  lighter  when  raised  ;  while  the  reverse  is  the 
case  with  water  in  oil,  since  the  difference  of  refraction 
causes  the  oil  particles  to  act  as  convex  lenses,  and  those 
of  water  like  concave  lenses. 

Other  errors  arise  from  the  phenomena  of  motion  visible 
under  the  microscope.  A  dry  filament  of  cotton,  or  other 
fabric  absorbing  moisture,  will  often  oscillate  and  twist 
in  a  curious  way. 

If  alcohol  and  water  are  mixed,  the  particles  suspended 
acquire  a  rapid  motion  from  the  currents  set  up,  which 
continues  till  the  fluids  are  thoroughly  blended.  Nearly 
all  substances  in  a  state  of  minute  division  exhibit,  when 
suspended  in  fluid,  a  movement  called  the  "  Brownonian 
motion,"  from  Dr.  Robert  Brown,  who  first  investigated 
it.  It  is  a  peculiar,  uninterrupted,  dancing  movement,  the 
cause  of  which  is  still  unexplained.  These  movements, 
as  all  others,  appear  more  energetic  when  greatly  magni- 
fied by  strong  objectives.  It  requires  care  to  discriminate 


54  THE    MICROSCOPIST. 

between  such  motions  and  the  vital  or  voluntary  motions 
of  organized  bodies. 

The  inflection  or  diffraction  of  light  is  another  source 
of  error,  since  the  sharpness  of  outline  in  an  object  is  thus 
impaired.  The  shadow  of  an  opaque  object  in  a  divergent 
pencil  of  light  presents,  not  sharp,  well-defined  edges,  but 
a  gradual  shading  off,  from  which  it  is  inferred  that  the 
rays  do  not  pass  from  the  edge  of  the  object  in  the  same 
line  as  they  come  to  it.  This  is  in  consequence  of  the 
undulatory  nature  of  light.  When  any  system  of  waves 
meets  with  an  obstacle,  subsidiary  systems  of  waves  will 
be  formed  round  the  edge  of  the  obstacle  and  be  propagated 
simultaneously  with  the  original  undulations.  For  a  cer- 
tain space  around  the  lines  in  which  the  rays,  grazing  the 
edge  of  the  opaque  body,  would  have  proceeded,  the  two 
systems  of  undulation  will  intersect  and  produce  the  phe- 
nomena of  interference.  If  the  opaque  body  be  very  small, 
and  the  distance  from  the  luminous  point  proportionally 
large,  the  two  pencils  formed  by  inflection  will  intersect, 
and  all  the  phenomena  of  interference  will  become  evident. 
Thus,  if  the  light  be  homogeneous,  a  bright  line  of  light 
will  be  formed  under  the  centre  of  the  opaque  object,  out- 
side of  which  will  be  dark  lines,  and  then  bright  and  dark 
lines  alternately.  If  the  light  be  compound  solar  light,  a 
series  of  colored  fringes  will  be  formed.  In  addition  to 
the  results  of  inflection,  oblique  illumination  at  certain 
angles  produces  a  double  image,  or  a  kind  of  overlying 
shadow,  sometimes  called  the  "diffraction  spectrum," 
although  due  to  a  different  cause.  No  rules  can  be  given 
for  avoiding  errors  from  these  optical  appearances,  but 
practice  will  enable  one  to  overcome  them,  as  it  were, 
instinctively. 

Testing  the  Microscope. — The  defining  power  of  an  in- 
strument depends  on  the  correction  of  its  spherical  and 
chromatic  aberrations,  and  excellence  may  often  be  ob- 
tained with  objectives  having  but  a  moderate  angle  of 


USB    OF    THE    MICROSCOPE.  55 

aperture.  It  may  be  known  by  the  sharp  outline  given 
to  the  image  of  an  object,  which  is  not  much  impaired  by 
the  use  of  stronger  eye  pieces. 

Resolving  power  is  the  capability  an  instrument  has  of 
bringing  out  the  fine  details  of  a  structure,  and  depends 
mainly  on  the  angle  of  aperture  of  the  objective,  or  the 
angle  formed  by  the  focus  and  the  extremities  of  the 
diameter  of  the  lens.  On  this  account  the  increase  of  the 
angle  of  aperture  has  been  a  chief  aim  with  practical 
opticians. 

Penetrating  power  is  the  degree  of  distinctness  with 
which  the  parts  of  an  object  lying  a  little  out  of  focus 
may  be  seen.  Objectives  which  have  a  large  angle  of 
aperture,  and  in  consequence  great  resolving  power,  are 
often  defective  in  penetration,  their  very  perfection  only 
permitting  accurate  vision  of  what  is  actually  in  focus. 
Hence  for  general  purposes  a  moderate  degree  of  angular 
aperture  is  desirable. 

Flatness  of  field  of  view  is  also  a  necessity  for  accurate 
observation.  Many  inferior  microscopes  hide  their  im- 
perfection in  this  respect  by  a  contracted  aperture  in  the 
eye-piece,  by  which,  of  course,  only  a  part  of  the  rays 
transmitted  by  the  objective  are  available. 

Object-glasses  whose  focal  length  is  greater  than  half 
an  inch  are  called  low  powers.  Medium  powers  range 
from  one-half  to  one-fifth  of  an  inch  focal  length,  and  all 
objectives  less  than  one-fifth  are  considered  high  powers. 

For  definition  with  low  power  objectives,  the  pollen 
grains  of  hollyhock,  or  the  tongue  of  a  fly,  or  a  specimen 
of  injected  animal  tissue,  will  be  a  sufficient  test.  The 
aperture  should  be  enough  to  give  a  bright  image,  and 
the  definition  sufficient  for  a  clear  image.  A  section  of 
wood,  or  of  an  echinus  spine,  will  test  the  flatness  of  the 
field. 

Medium  powers  are  seldom  used  with  opaque  objects 
unless  they  are  very  small,  but  are  most  useful* with 


56  THE    MICROSCOPIST. 

properly  prepared  transparent  objects.  A  good  half-inch 
objective  should  show  the  transverse  markings  between 
the  longitudinal  ribs  on  the  scales  of  the  Hipparchia 
janira,  butterfly  (Plate  I,  Fig.  27),  and  the  one-fourth  or 
one-fifth  should  exhibit  markings  like  exclamation  points 
on  the  smaller  scales  of  Podura  plumbea  (Plate  I,  Fig.  28) 
or  Ijepidocyrtis. 

High  power  objectives  are  chiefly  used  for  the  most 
delicate  and  refined  investigations  of  structure,  and  are 
not  so  suitable  for  general  work.  It  is  with  these  glasses 
that  angular  aperture  is  so  necessary  to  bring  out  striae, 
and  dots,  and  other  delicate  structures,  under  oblique 
illumination.  For  these  glasses,  the  best  tests  are  the 
siliceous  envelopes  of  diatoms,  as  the  Pleurosigma  angu- 
latum,  Surirella  gemma,  G-rammataphora  subtilissima ;  or 
the  wonderful  plates  of  glass  artificially  ruled  by  M.  Ro- 
bert, and  known  as  Nobert's  test. 

The  latter  test  is  a  series  of  lines  in  bands,  the  distance 
between  the  lines  decreasing  in  each  band,  until  their 
existence  becomes  a  matter  of  faith  rather  than  of  sight, 
since  no  glass  has  ever  revealed  the  most  difficult  of  them. 
The  test  plate  has  nineteen  bands,  and  their  lines  are 
ruled  at  the  following  distances:  Band  1,  y^^th  of  a 
Paris  line  (to  an  English  inch  as  .088  to  1.000,  or  as  11  to 
125).  Band  2,  T^O^-  Band  3,  s^th.  Band  5, 
Band  9,  I0'^th.  Band  13,  ^th.  Band  17, 
Band  19,  TI,i^th. 

It  is  said  that  Hartnack's  immersion  system  ~No.  10 
and  oblique  light  has  resolved  the  lines  in  the  15th  band, 
in  which  the  distance  of  lines  is  about  ^T  J^th  of  an  inch. 

The  surface  markings  of  minute  diatoms  are  also  ex- 
cessively fine.  Those  of  Pleurosigma  formosum.  being  from 
20  to  32  in  y^^th  of  an  inch  ;  of  P.  hippocampus  and  P. 
attenuatum  about  40 ;  P.  angulatum  46  to  52  ;  Navicula 
rhomboides  60  to  111 ;  and  Amphipleura  pelludda  120  to 
130.  *  This  latter  has  been  variously  estimated  at  100,000 


PLATE  I. 


FIG.  28. 


FIG.  27. 


Scale  of  Hipparchia  Janira. 


Scales  of  Fodura  plumbea :— A,  large 
strongly  marked  scale;  B,  small  scale 
more  faintly  marked;  c,  portion  of  an 
injured  scale,  showing  the  nature  of  the 
markings. 


FIG. 29. 


, 


*  0  •  »  I 

•**.• 


Pleuroxigma  angtilntum :— A,  entire  frustule,  as  seen 
under  a  power  of  500  diam.;  B,  hexagonal  aerolation, 
as  seen  under  a  power  of  1300  diam.;  c,  the  same, 
as  seen  under  a  power  of  15,000  diam. 


USE    OF    THE    MICROSCOPE. 


57 


to  130,000  in  an  inch.  It  has  been  resolved  by  Dr.  Wood- 
ward with  the  y'gth  immersion  of  Powell  and  Lealand, 
using  oblique  sunlight  through  a  solution  of  airnnonio- 
sulphate  of  copper. 

The  longitudinal  lines  (between  the  transverse)  of  the 

FIG.  30. 


Valve  of  Surirella  Gemma. 
a.  Transverse  ridges.    6.  Longitudinal  lines,    c.  The  same,  resolved  into  areolations. 


Surirella  gemma  are  estimated  at  30  to  32  in  T^o^n  °f  a 
millimetre,  and  the  markings  on  Grammataphora  subtilis- 
sima  Sit  32  to  34  in  the  same  distance. 


FIG.  31. 
a. 


Grammataphora  Subtilissima. 
a.  Valve.    6.  Transverse  lines. 


J.  D.  Moller  has  produced  a  very  excellent  test-plate, 
containing  twenty  diatoms,  with  descriptions,  according 
to  their  value  as  tests. 


58  THE    MICROSCOPIST. 

The  Pleurosigma  angulatum  (Plate  I,  Fig.  29),  with  suit- 
able power  and  illumination,  should  show  distinct  hexag- 
onal areolations.  The  Surirella  gemma  (Fig.  30)  shows  a 
series  of  fine  transverse  lines  across  the  ridges  which  run 
from  the  edge  to  the  central  line.  The  finest  of  these 
ridges  are  not  always  readily  seen,  and  the  transverse 
ones  are  only  to  he  mastered  by  toil  and  patience. 

The  Grammatapliora  subtilissima  (Fig.  31)  shows  trans- 
verse lines  (or  rows  of  dots)  along  the  edge,  and  sometimes 
a  double  series  of  oblique  lines. 


CHAPTER   Y. 


MODERN  METHODS   OF    EXAMINATION. 

MICROSCOPY  does  not  limit  its  researches  to  optical 
enlargement,  but  seeks  to  comprehend  elementary  struc- 
ture, and  its  methods  vary  according  to  the  object  imme- 
diately in  view.  It  may  seek  merely  to  discern  the  form 
or  morphology  of  the  elementary  parts  or  their  peculiar 
functions.  It  may  be  concerned  with  inorganic  forms, 
normal  or  pathological  anatomy,  or  with  physiology. 
Each  department  of  pursuit  will  suggest  some  variation, 
yet  a  general  plan  of  operation  is  possible. 

Coarse,  and  moderately  large  objects,  as  a  small  insect, 
a  piece  of  vegetable  tissue,  etc.,  may  be  observed  by  plac- 
ing it  in  the  forceps,  or  on  the  stage  of  the  instrument, 
under  an  objective  of  low  power,  but  ordinarily  a  consid- 
erable degree  of  preparation  is  needed  in  order  to  acquire 
a  true  idea  of  structure. 

Most  of  the  tissues  to  be  examined  are  in  a  moist  con- 


MODERN  METHODS  OF  EXAMINATION.        59 

dition,  and  many  require  to  be  dissected  or  preserved  in 
fluid.  This  has  much  to  do  with  the  appearance  of  the 
object  in  the  microscope.  If  fibres  or  cells  are  imbedded 
in  connective  tissue  or  in  fluids,  of  which  the  refractive 
power  is  the  same  as  their  own,  they  cannot  be  perceived 
even  with  the  best  glasses,  and  artificial  means  must  be 
resorted  to  that  they  may  become  visible.  The  refractive 
power  of  different  media  causes  different  appearances. 
Thus  a  glass  rod  lying  in  water  is  easily  seen,  but  in 
Canada  balsam,  whose  refractive  power  is  nearly  the  same 
as  glass,  it  is  barely  seen  as  a  flat  band,  and  in  the  more 
highly  refractive  anise  oil  it. presents  the  appearance  of  a 
cavity  in  the  oil. 

During  life  the  cavities  and  fissures  in  animal  tissues, 
in  consequence  of  the  different  refractive  power  of  their 
contents  and  the  change  which  takes  place  soon  after 
death,  exhibit  a  sharpness  and  softness  of  outline  which 
is  seldom  seen  in  preparations. 

There  are  two  methods  of  microscopic  investigation  or 
of  preparation  preliminary  to  direct  observation:  1.  Me- 
chanical, for  the  separation  and  isolation  of  the  elemen- 
tary parts.  2.  Chemical,  which  dissolve  the  connecting 
material,  or  act  on  it  differently  than  on  other  elements. 

For  minute  dissection  a  great  variety  of  instruments 
have  been  proposed,  but  by  practiced  hands  more  can  be 
accomplished  in  shorter  time  by  simple  means  than  with 
complicated  ones.  Two  or  three  scalpels,  or  small  ana- 
tomical knives,  a  pair  of  small  scissors,  such  as  is  used  in 
operations  on  the  eye,  and  fine-pointed  forceps,  will  be 
found  useful.  But  the  most  serviceable  instruments  are 
dissecting-needles,  such  as  the  microscopist  may  make  for 
himself.  A  common  sewing-needle,  with  the  eye  end 
thrust  into  a  cedar  stick  about  three  inches  long  and  one- 
fourth  of  an  inch  diameter,  will  answer  the  purpose.  The 
point  should  not  project  so  far  as  to  spring,  and  if  desired, 
a  cutting  edge  can  be  given  to  it  by  a  hone. 


60 


THE    MICROSCOPIST. 


The  light  should  be  concentrated  on  the  work  by  means 
of  a  bull's-eye  condenser,  and  as  far  as  possible,  the  dis- 
section should  be  carried  on  with  the  unassisted  eye. 
Very  often  the  work  is  so  fine  that  a  magnifying  glass, 
or  simple  microscope,  fixed  to  a  suitable  arm,  will  be 
needed.  A  large  Coddington  lens,  an  inch  and  a  half  in 
diameter,  such  as  is  used  frequently  by  miners,  will  be 
useful.  Sometimes  it  is  necessary  to  resort  to  the  dissect- 
ing microscope,  which  is  a  simple  lens,  of  greater  or  less 
power,  arranged  with  rack  and  pinion,  mirror,  etc. 

The  specimen  may  be  dissected  under  water,  in  a  glass 
or  porcelain  dish,  or  a  trough  made  of  gutta-percha,  etc. 
Dr.  Lawson's  binocular  dissecting  microscope  (Fig.  32)  is 


FIG.  32. 


Lawson's  Binocular  Dissecting  Microscope. 


a  most  useful  form,  as  both  eyes  may  be  used.  Loaded 
corks,  with  sheet  lead  fastened  to  their  under  surface, 
may  be  used  to  pin  the  subject  on  for  greater  facility  in 
dissection.  Rests,  or  inclined  planes  of  wood,  one  on  each 
side  of  the  trough,  will  give  steadiness  to  the  hands. 
Camels'-hair  pencils  for  the  removal  of  dust  and  extrane- 


MODERN  METHODS  OP  EXAMINATION.        61 

ous  elements,  and  for  spreading  out  thin  and  delicate  tis- 
sues or  sections,  are  indispensable.  Pipettes,  or  glass 
tubes,  one  end  of  which  can  be  covered  with  the  end  of 
the  finger,  may  serve  to  convey  a  drop  of  fluid  or  a  small 
specimen  from  a  bottle. 

Preparation  of  Loose  Textures. — If  the  formed  elements 
of  tissue  do  not  combine  in  a  solid  mass,  it  is  only  neces- 
sary to  place  a  small  quantity  on  a  glass  slide  and  cover 
it  with  a  plate  of  thin  glass.  If  the  elements  are  too  close 
for  clear  definition  under  the  microscope,  a  drop  of  fluid 
may  be  added.  The  nature  of  this  fluid,  however,  is  not 
a  matter  of  indifference.  Some  elements  are  greatly 
changed  by  water,  etc.,  and  it  becomes  important  to  con- 
sider the  fluid  which  is  most  indifferent.  Glycerin  and 
water,  one  part  to  nine  of  water,  will  serve  well  for  most 
objects.  Animal  tissues  are  often  best  treated  with  aque- 
ous humor,  serum,  or  iodized  serum.  A  weak  solution  of 
salt,  7.5  grains  chloride  of  sodium  to  1000  grains  of  dis- 
tilled water,  serves  for  many  delicate  structures.  (See 
section  on  Fluid  Media.) 

Preparation  by  Teasing. — A  minute  fragment  of  tissue 
should  be  placed  in  a  drop  of  fluid  on  a  slide,  and  torn  or 
unravelled  by  two  sharp  needles.  This  is  accomplished 
more  easily  after  maceration,  and  sometimes  it  is  neces- 
sary to  macerate  in  a  substance  which  will  dissolve  the 
connecting  material.  This  picking  or  teasing  should  be 
slowly  and  accurately  performed.  Beginners  often  fail 
of  a  good  preparation  by  ceasing  too  soon,  as  well  as  by 
having  too  large  a  specimen.  The  most  delicate  manipu- 
lation is  required  to  isolate  nerve-cells  and  processes. 

Preparation  by  Section. — A  section  of  soft  substance  may 
be  made  with  a  sharp  knife  or  scalpel,  or  with  a  pair  of 
scissors  curved  on  the  upper  side.  A  section  cut  with  the 
latter  will  taper  away  at  the  edges  so  as  to  afford  a  view 
of  its  structure. 


62  THE    MICROSCOP1ST. 

Valentin's  double  knife  (Fig.  33)  is  used  for  soft  tissues 
where  only  a  moderate  degree  of  thinness  is  needed.  The 
blades  should  be  wet,  or  the  section  made  under  water. 

Soft  substances  often  require  hardening  before  sections 
can  be  made  The  most  simple  and  best  method  is  that 
of  freezing,  by  surrounding  the  specimen  with  a  freezing 
mixture,  when  it  may  be  cut  with  a  cold  knife.  Small 
pieces  of  tissue  may  be  hardened  in  absolute  alcohol,  fre- 
quently renewed.  Chromic  acid,  in  solution  of  one-fourth 
to  two  per  cent.,  is  often  used  for  animal  tissues,  or  bichro- 
mate of  potash  of  the  same  strength.  A  solution  of  one- 
fifth  to  one-tenth  per  cent,  of  perosmic  acid  or  of  chloride 
of  palladium  is  also  recommended. 

Soft  tissues  often  require  imbedding  in  a  concentrated 
solution  of  gum  or  of  wax,  spermaceti,  or  paraffin  tem- 
pered with  oil.  In  this  case  sections  may  be  made  readily 
by  means  of  a  section-cutter.  For  imbedding  in  wax,  etc., 

FIG.  33. 


Valentin's  Knife. 

the  specimen  must  be  hardened  in  alcohol,  then  treated 
with  oil  of  cloves  or  turpentine,  and  the  section  should  be 
mounted  in  Canada  balsam  or  Dammar  varnish. 

Sections  of  hard  substances,  or  of  those  imbedded,  are 
often  made  by  machines  invented  for  the  purpose.  One 
of  the  simplest  is  (Fig.  34)  an  upright  hollow  cylinder, 
with  a  kind  of  piston,  pushed  upwards  by  a  fine  screw. 
The  upper  end  of  the  cylinder  carrying  the  specimen  ter- 
minates in  a  flat  table,  along  which  a  sharp  knife  or  flat 
razor  is  made  to  slide.  At  one  side  of  the  tube  is  a 
binding-screw  for  holding  the  specimen  steady.  A  sec- 


MODERN  METHODS  OF  EXAMINATION.        63 

tion  may  be  cut  by  such  an  instrument  after  inserting 
the  structure  desired  in  a  piece  of  carrot,  etc.,  which  may 
be  placed  in  the  tube ;  or  the  tube  may  be  filled  with  wax, 
etc.,  and  the  specimen  imbedded.  Bones,  teeth,  shells, 
corals,  minerals,  etc.,  require  to  be  cut  with  fine  saws,  or 
a  disk  of  thin  iron  on  a  lapidary's  wheel,  and  filed  or 
ground  down  to  the  requisite  thinness,  then  polished  with 
emery,  rouge,  etc.  The  green  oxide  of  chromium  has 
been  suggested  to  me  as  a  useful  polishing  powder  for 
hard  substances.  For  calcareous  substances,  files  and 
hones  will  suffice  to  reduce  the  thickness,  and  putty 

FIG.  34. 


Section-Cutter. 


powder  or  jewellers'  rouge  for  polishing.     They  should 
be  mounted  in  Canada  balsam. 

Staining  Tissues. — Certain  elements,  not  previously  visi- 
ble, can  often  be  made  evident  by  certain  coloring  matters, 
by  wrhich  some  constituents  become  more  quickly  or  more 
thoroughly  stained  than  others.  The  "  germinal  matter," 
or  "bioplasm"  of  Dr.  Beale,  identical  with  the  "proto- 
plasm "  or  "  sarcode  "  of  other  observers,  may  thus  be  dis- 
tinguished from  the  "  formed  materials  "  or  "  tissue  ele- 


64 


THE    MICROSCOPIST. 


ment,"  which  are  the  products  of  its  activity.  Carmine, 
auilin,  haematoxylin,  and  picric  acid,  are  used  for  staining 
by  imparting  their  own  color  to  tissues ;  while  nitrate  of 
silver,  chloride  of  gold,  chloride  of  palladium,  and  peros- 
mic  acid  stain,  by  their  chemical  action,  often  under  the 
reducing  influence  of  light.  (See  Fluid  Media.} 

Injecting  Tissues. — Injections  of  the  vessels  in  animal 
tissues  are  resorted  to  either  to  exhibit  their  course  or  the 
structure  of  the  vascular  walls.  For  the  latter  purpose  a 
solution  of  nitrate  of  silver  is  commonly  employed,  for  the 
former  either  opaque  or  transparent  coloring  matter.  (See 
Fluid  Media.} 

The  injecting  syringe  (Fig.  35)  is  made  of  brass  or  Ger- 


FlG.  35. 


Injecting  Syringe. 

man  silver.  One  of  the  pipes  should  be  inserted  into  the 
principal  vessel,  as  the  aorta  of  a  small  animal,  the  um- 
bilical vein  of  a  fetus,  or  the  artery,  etc  ,  of  an  organ, 
and  should  be  securely  fastened  by  a  thread.  All  other 
open  vessels  should  be  tied.  The  solution  of  gelatin,  or 
other  matter  used,  should  be  strained,  so  as  to  be  free 
from  foreign  particles,  and  should  be  forced  into  the  ves- 
sels with  a  gentle,  steady  pressure  on  the  syringe. 

Injections  should  be  made  soon  after  the  death  of  the 
animal,  or  else  after  the  rigor  mortis  has  subsided. 


MODERN    METHODS    OF    EXAMINATION.  65 

Sometimes  the  syringe  is  substituted  by  a  self-acting 
apparatus,  consisting  of  a  Wolfe's  bottle,  containing  the 
fluid,  which  is  pressed  upon  by  a  column  of  air  from 
another  source,  and  driven  through  a  flexible  tube  to  the 
pipe  in  the  bloodvessel. 

The  older  anatomists  used  colored  plaster  or  wax  to 
demonstrate  the  arteries  and  veins,  but  modern  histology 
requires  finer  materials.  Isinglass  or  gelatin,  colored,  and 
injected  warm,  or  a  solution  of  colored  glycerin,  are  now 
resorted  to.  The  former  serves  for  opaque,  and  the  latter 
for  fine,  transparent  injections. 

The  art  of  injecting  can  only  be  learned  by  practice, 
yet  perseverance,  in  despite  of  many  failures,  will  insure 
success. 

The  liver,  kidney,  etc.,  may  be  injected  separately,  and 
it  is  often  desirable  to  use  various  colors  for  the  different 
sets  of  vessels.  After  injection  thin  slices  may  be  cut  off 
and  mounted  in  fluid  or  balsam. 

Preparation  in  Viscid  Media. — Dr.  Beale  has  proposed  a 
method  of  preparing  animal  and  vegetable  tissues  for  ex- 
amination with  the  very  highest  powers,  which  has  led  to 
valuable  results.  It  consists  in  using  pure  glycerin  or 
strong  syrup,  instead  of  watery  solutions.  In  this  way 
an  amount  of,  pressure  may  be  applied  to  sections,  in  order 
to  render  them  thin  enough  for  examination,  which  would 
be  destructive  to  specimens  in  water,  while  the  preserva- 
tive action  of  the  media  prevents  change  in  the  structure. 
It  is  necessary  to  soak  the  specimen  some  time,  and  the 
strength  of  the  fluid  should  be  gradually  increased  until 
the  tissue  is  permeated  by  the  strongest  that  can  be  ob- 
tained. Dr.  Beale  has  found  that  minute  dissection  is 
much  more  readily  performed  in  such  fluids,  and  that 
even  very  hard  textures,  as  bone  and  teeth,  may  be  softened 
by  them,  especially  if  acetic  acid  is  added,  so  as  to  permit 
thin  sections  to  be  made  with  a  knife.  He  recommends 

5 


66  THE    MICROSCOPIST. 

vessels  to  be  first  injected,  as  with  fine,  transparent  blue, 
and  the  germinal  matter  to  be  stained  with  carmine.  A 
few  drops  of  a  solution  of  chromic  acid,  or  bichromate  of 
potash,  so  as  to  impart  to  the  glycerin  a  pale  straw  color, 
serves  to  harden  even  the  finest  nerve-structures.  Acetic 
acid,  and  other  reagents  also,  are  much  more  satisfactorily 
used  with  glycerin  than  with  water.  If  syrup  is  used, 
camphor,  carbolic  acid,  etc  ,  must  be  employed  to  prevent 
the  growth  of  fungi,  but  pure  glycerin  is  free  from  this 
inconvenience. 

A  great  advantage  of  this  mode  of  investigation  con- 
sists in  the  fact  that  a  specimen  thus  prepared  is  already 
mounted,  and  needs  but  a  proper  cement  to  the  glass  cover 
and  a  finish  to  the  slide,  when  it  is  ready  for  the  cabinet. 


FLUID  MEDIA. 
1.  INDIFFERENT  FLUIDS. 

The  vitreous  hnmor,  amniotic  liquor,  serum,  etc.,  which 
form  the  usual  fluids  termed  indifferent,  always  contain 
what  Prof.  Graham  designated  colloid  and  crystalloid 
substances.  In  1 000  parts  there  are  about  4  parts  of  col- 
loid (albumen)  and  7.5  of  crystalloid  substance  (chloride 
of  sodium). 

The  iodine  serum  of  Schultze  consists  of  the  amniotic 
fluid  of  the  embryo  of  a  ruminant,  to  which  about  6  drops 
of  tincture  of  iodine  to  the  ounce  is  added  A  small  piece 
of  camphor  will  preserve  this  from  decomposition  a  long 
time.  A  substitute  for  this  is  composed  of  1  ounce  of 
white  of  egg,  9  ounces  of  water,  2  scruples  chloride  of 
sodium,  with  the  corresponding  quantity  of  tincture  of 
iodine. 


MODERN  METHODS  OF  EXAMINATION.        61 


2.  CHEMICAL  REAGENTS. 

The  greatest  care  should  be  used  with  these,  that  the- 
instruraent  and  glasses  may  be  preserved.  A  small  drop,, 
applied  by  a  glass  rod  drawn  out  to  a  point  to  the  edge  of 
the  glass  cover,  will  suffice  in  most  cases. 

Sulphuric  Add. — Concentrated  is  used  to  isolate  the- 
cells  of  horny  structures,  as  hair,  nails,  etc.  Dilute  (1  part 
to  2-3  of  water)  gives  to  cellulose,  previously  dyed  with, 
iodine,  a  blue  or  purple  color,  and,  when  mixed  with 
sugar,  a  rose-red  to  nitrogenous  substances  and  bile.  0.1 
to  1000  of  water,  at  a  temperature  of  35-40°  C.,  resolves 
connective  tissue  into  gelatin  and  dissolves  it,  so  as  to  be 
useful  in  isolating  muscular  fibres. 

Nitric  Acid. — Diluted  with  4  or  5  parts  water,  separates 
the  elementary  parts  of  many  vegetable  and  animal  tis- 
sues when  they  are  boiled  or  macerated  in  it.  With  chlo- 
rate of  potash  it  is  still  more  energetic,  but  caution  is 
needed  in  its  use. 

Muriatic  Acid,  Strong. — Used  for  dissolving  intercellular 
substance,  as  in  the  tubes  of  the  kidney,  etc.  Dilute  for 
dissolving  calcareous  matter. 

Chromic  acid,  J  to  2  per  cent,  solution  for  hardening 
nerves,  brain,  etc. 

Oxalic  acid,  to  15  parts  water,  causes  connective  tissue 
to  swell  and  become  transparent,  while  albuminoid  ele- 
ments are  hardened.  Preserves  well  delicate  substances, 
as  rods  of  retina,  etc. 

Acetic  acid  makes  nuclei  visible  and  connective  tissue 
transparent,  so  as  to  exhibit  muscles,  nerves,  etc.,  other- 
wise invisible. 

Iodine  (\  grain  of  iodine,  3  grains  iodide  of  potassium, 
1  ounce  of  water)  turns  starch  blue  and  cellulose  brown. 

Caustic  potash  or  soda  renders  many  structures  trans- 
parent. 


68  THE    MICROSCOPIST. 

Lime-water  or  baryta-water  is  used  for  investigating  con- 
nective structures,  especially  tendon,  as  maceration  en- 
ables the  needle  to  divide  its  fibril! a. 

Chloride  of  Sodium. — Solutions  of  this  salt  for  indifferent 
media  should  always  have  some  colloid,  as  albumen  or 
gum-arabic  added  (7.5  grains  in  1000  grains  of  water  for 
delicate  structures). 

JBicfoomate  of  potash  is  used  in  stronger  solution  for  the 
same  purposes  as  chromic  acid. 

Mutter's  eye-fluid  for  hardening  the  retina,  and  preserv- 
ing delicate  embryos,  etc.,  consists  of  bichromate  of  potass., 
2  grammes  ;  sulphate  of  soda,  1  gramme  ;  distilled  water, 
100  grammes. 

Alcohol  dissolves  resins  and  many  vegetable  coloring 
matters  ;  renders  most  vegetable  preparations  more  trans- 
parent, and  albuminous  animal  tissues  more  opaque. 

Acetic  acid  and  alcohol,  1  part  of  each  to  2  of  water, 
renders  connective  tissue  transparent,  and  albuminoid  tis- 
sue prominent.  The  proportions  can  be  varied. 

Alcohol  and  soda  (8-10  drops  of  strong  solution  of  caustic 
soda  to  each  ounce)  renders  many  tissues  very  hard  and 
transparent.  Beale  recommends  it  for  embryonic  struc- 
tures. 

Ether  dissolves  resins,  oils,  and  fat. 

Turpentine  renders  dried  animal  sections  transparent. 

Oil  of  cloves  acts  as  turpentine. 

Solution  of  chloride  of  zinc,  iodine,  and  iodide  of  potassium, 
is  recommended  by  Schacht  as  a  substitute  for  iodine  and 
sulphuric  acid  to  color  vegetable  cells,  etc.  Zinc  is  dis- 
solved in  hydrochloric  acid,  and  the  solution  is  evaporated 
to  syrupy  consistence  in  contact  with  metallic  zinc.  This 
is  saturated  with  iodide  of  potassium,  iodine  added,  and 
the  solution  diluted  with  water.  Wood  cells,  after  boiling 
in  caustic  potash,  are  stained  blue  by  it. 

Boracic  acid,  used  by  Prof.  Brucke  to  separate  the  ele- 
ments of  red  blood-corpuscles. 


MODERN  METHODS  OF  EXAMINATION.  69 

3.  STAINING  FLUIDS. 

Thier setts  Carmine  Fluids. 
a.  RED  FLUID. 

1.  Carmine, 1  part. 

Caustic  ammonia,       .         .         .         .         .       1     " 

Distilled  water, 3  parts.     Filter. 

2.  Oxalic  acid, 1  part. 

Distilled  water, 22  parts. 

1  part  of  carmine  solution  to  8  parts  of  the  acid  solution,  add  12  parts 
absolute  alcohol.     Filter.     After  staining  wash  in  80  per  cent,  alcohol. 

b.  LILAC  FLUID. 

Borax,        .        .       ..:       •         •         •         •       4  parts. 

Distilled  water, 56    " 

Dissolve  and  add, 

Carmine,  .         .         .         .         .         .         .1  part. 

Mix  with  twice  the  volume  of  absolute  alcohol  and  filter. 

Beetle's  Carmine  Fluids. 

Carmine,  .......  10  grains. 

Strong  liquor  ammonia,  £  drachm. 

Glycerin,  .......  2  ounces. 

Distilled  water,         .        .         .        .  2      " 

Alcohol, £  ounce. 

Dissolve  the  carmine  in  the  ammonia  in  a  test-tube  by  aid  of  heat ;  boil 
it  and  cool  and  add  the  other  ingredients.     Filter. 

Acid  Carmine  Fluid. — Mix  ammoniacal  solution  of  car- 
mine with  acetic  acid  in  excess  and  filter.  This  is  said 
to  stain  diffusely,  but  adding  glycerin  with  muriatic  acid 
(1 :  200),  concentrates  the  color  in  the  cell-nucleus. 

Anilin  (or  Magenta]  Red  Fluid. 

Fuchsin  (crystal), 1  centigramme. 

Absolute  alcohol,     ....        20-25  drops. 
Distilled  water,        .....     15  cubic  centim. 

Anilin  Blue  Fluid. — Anilin  blue,  treated  with  sulphuric 
acid  and  dissolved  in  water  till  a  deep  cobalt  color  is 
obtained. 


70  THE    MICROSCOPIST. 

Blue  Fluid  from  Indigo  Carmine. 

Oxalic  acid,    .......       1  part. 

Distilled  water,       .         .        .        .        .        20-30  parts. 

Indigo  carmine  to  saturation. 

Logwood  Violet  Fluid. 

1.  Ha3matoxylin,    .         .         .         .  .20  grains. 
Absolute  alcohol,        .         .         .         .         .       £  ounce. 

2.  Solution  of  2  grains  of  alum  to  1  ounce  of  water. 

A  few  drops  of  the  first  solution  to  a  little  of  the  second  in  a  watch- 
glass,  etc. 

Picro-Carmine  Fluid. — Filter  a  saturated  solution  of 
picric  acid,  and  add,  drop  by  drop,  strong  ammoniacal 
solution  of  carmine  till  neutralized. 

Nitrate  of  Silver  Fluid.  —  Fresh  membranous  tissues, 
exposed  to  0.5  to  0.2  per  cent,  solution  of  nitrate  of  silver, 
washed  and  exposed  to  light,  often  show  a  mosaic  of  epi- 
thelium, etc. 

Osmie  Acid. — y^th  to  1  per  cent,  solution  stains  the 
medulla  of  nerves,  etc.,  black. 

Chloride  of  Gold. — The  solution  should  be  similar  to  that 
of  nitrate  of  silver.  Exposure  to  light  stains  the  nerves, 
etc.,  a  violet  or  red  color. 

Prussian  Blue. — After  immersing  a  tissue  in  0.5  to  1 
per  cent,  solution  of  a  protosalt  of  iron,  dip  it  in  a  1  per 
cent,  solution  of  ferrocyanide  of  potassium. 

Other  Staining  Fluids. — Marked  effects  are  often  pro- 
duced by  the  use  of  the  violet,  blue,  and  other  inks  in  the 
market.  Thus  I  succeeded  in  some  demonstrations  of 
nerve  plexuses  in  muscle  better  than  in  any  other  way. 
I  suspect  the  particular  ink  employed  contained  a  large 
per  cent,  of  soluble  Prussian  blue. 

4.  INJECTING  FLUIDS. 

For  opaque  injection  several  plans  have  been  devised. 
Eesinous  and  gelatinous  substances,  variously  colored,  are 


MODERN    METHODS    OF    EXAMINATION.  71 

most  usual.  Lieberkuhn  used  tallow,  varnish,  and  tur- 
pentine, colored  with  cinnabar  ;  and  Hyrtl,  whose  prepa- 
rations have  been  much  admired,  follows  a  similar  plan. 
He  evaporates  pure  copal  or  mastic  varnish  to  the  consis- 
tence of  syrup,  and  grinds  one-eighth  as  much  cinnabar 
and  a  little  wax  with  it  on  a  slab.  For  fine  injections  this 
is  diluted  with  ether. 

For  a  bright  red,  the  cinnabar  may  be  mixed  with  a 
little  carmine 

For  a  yellow  color,  the  chromate  of  lead,  prepared  by 
mixing  solutions  of  acetate  of  lead  (36  parts  to  2  ounces 
of  water),  and  red  chromate  of  potash  (15  parts). 

White  may  be  made  with  zinc-white  or  carbonate  of 
lead — 4J  ounces  of  acetate  of  lead  in  16  ounces  of  water, 
mixed  with  3  J  ounces  carbonate  of  soda  in  16  ounces. 

For  gelatinous  injections  the  coloring  matter  is  com- 
bined with  jelly,  prepared  by  soaking  fine  gelatin  in  cold- 
water  for  several  hours,  then  dissolving  in  a  water-bath 
and  filtering  through  flannel. 

By  injecting  gelatinous  fluid  solutions  of  various  salts, 
the  coloring  matter  may  be  left  in  the  vessels  by  double 
decomposition. 

A  red  precipitate,  with  iodide  of  potassium  and  bichlo- 
ride of  mercury. 

A  blue,  by  ferrocyanide  of  potassium  and  peroxide  of 
iron,  etc. 

Dr.  Goadby's  formula  for  a  yellow  color  is : 

Saturated  solution  of  bichromate  of  potassium,  .     8  ounces. 
Water,          .  .      .         ...         .         .';*     .     8       " 

Gelatin,        .  ,|    ..     ,.«., 2       " 

Saturated  solution  of  acetate  of  lead, .        .         .8  ounces. 

Water,         .         .'       ff 8       " 

Gelatin,        ....         .         .         .         .         ;        .     2       " 

For  gelatinous  injections,  both  the  fluid  and  the  subject 
should  be  as  warm  as  may  consist  with  convenience. 
Camphor  also  should  be  added  to  prevent  mould. 


72  THE    MICROSCOPIST. 

For  transparent  injections,  gelatin  may  be  used  combined 
with  colored  solutions,  or  still  better,  glycerin,  which  may 
be  used  cold. 

Thiersch's  Blue. — Half  an  ounce  of  warm  concentrated 
solution  (2: 1)  of  fine  gelatin  is  mixed  with  6  cubic  centim- 
etres of  a  saturated  solution  of  sulphate  of  iron.  In 
another  vessel,  1  ounce  of  the  gelatin  solution  is  mixed 
with  12  cubic  centimetres  of  saturated  solution  of  ferro- 
cyanide  of  potassium,  to  which  12  cubic  centimetres  of 
saturated  solution  of  oxalic  acid  is  added.  When  cold, 
add  the  gelatinous  solution  of  sulphate  of  iron  drop  by 
drop,  with  constant  stirring,  to  the  other.  Warm  it, 
still  stirring,  and  filter  through  flannel. 

Gerlach's  Carmine. — Dissolve  5  grammes  (77  grains)  of 
fine  carmine  in  4  grammes  (70  grains)  of  water  and  J 
gramme  (8  drops)  of  liquor  ammonia.  Let  it  stand  sev- 
eral days  (not  airtight),  and  mix  with  a  solution  of  6 
grammes  of  fine  gelatin  to  8  grammes  of  water,  to  which 
a  few  drops  of  acetic  acid  are  added. 

Thiersch's  Yellow. — Prepare  a  solution  of  chromate  of 
potash  (1 : 11),  and  a  second  solution  of  nitrate  of  lead,  of 
same  strength.  To  1  part  of  the  first  add  4  parts  of  solu- 
tion of  gelatin  (about  20  cubic  centimetres  to  80),  and  to 
2  parts  of  the  second  add  4  parts  of  gelatin  (40  cubic  cen- 
timetres to  80).  Mix  slowly  and  carefully,  heat  on  a 
water-bath,  and  filter  through  flannel. 

Equal  parts  of  Thiersch's  blue  and  yellow  carefully 
mixed  and  filtered  make  a  good  green. 

COLD   TRANSPARENT   INJECTIONS. 

Beale's  Blue. 

Glycerin,.         .  .  >         .         .       1  ounce. 

Alcohol,  .         ., 1      " 

Ferrocyanide  of  potassium,      ....  12  grains. 
Tincture  of  perchloride  of  iron,        .         .         .       1  drachm. 

Water, 4  ounces. 


MODERN  METHODS  OF  EXAMINATION.        73 

Dissolve  the  ferrocyanide  in  1  ounce  of  water  and  glyc- 
erin, and  the  muriated  tincture  of  iron  in  another  ounce. 
Add  the  latter  very  gradually  to  the  other,  shaking  often ; 
then  gradually  add  the  alcohol  and  water. 

Scale's  Finest  Blue. 

Price's  glycerin,         ......       2  ounces. 

Tincture  of  perchloride  of  iron,          .         .         .     10  drops. 
Ferrocj^anide  of  potassium,        ....       3  grains. 

Strong  hydrochloric  acid, .....       3  drops. 

Water,        .         .         .         .         .         .         .         .1  ounce. 

Mix  the  tincture  of  iron  with  1  ounce  glycerin  and  the 
ferrocyanide,  after  dissolving  in  a  little  water,  with  the 
other  ounce.  Add  the  iron  to  the  other  solution  gradu- 
ally, shaking  well.  Lastly,  add  the  water  and  hydro- 
chloric acid.  Sometimes  about  2  drachms  of  alcohol  are 
added. 

Mutter's  Blue. — This  is  made  by  precipitation  of  soluble 
Prussian  blue  from  a  concentrated  solution  by  means  of 
90  per  cent,  alcohol. 

Beale's  Carmine. — Mix  5  grains  of  carmine  with  a  few 
drops  of  water,  and  when  well  incorporated,  add  5  or  6 
drops  of  liquor  ammonia.  To  this  add  J  ounce  of  glyc- 
erin, and  shake  well.  Another  J  ounce  of  glycerin  con- 
taining 8  or  10  drops  of  acetic  or  hydrochloric  acid  is 
gradually  added.  It  is  then  diluted  with  J  ounce  of  glyc- 
erin, 2  drachms  of  alcohol,  and  6  drachms  of  water. 

Nitrate  of  Silver  Injection. — For  demonstrating  the  struc- 
ture of  the  bloodvessels,  the  animal  is  bled,  and  a  solution 
of  0.25  to  1  per  cent,  of  nitrate  of  silver,  or  a  mixture  of 
gelatin  with  such  a  solution,  is  used. 

5.  PRESERVATIVE  FLUIDS. 

Canada  Balsam. — This  is  perhaps  the  most  common 
medium  used.  When  an  object  is  not  very  transparent, 
and  drying  will  not  injure  it,  balsam  will  do  very  well, 


74  THE    MICROSCOPIST. 

but  it  is  not  adapted  to  moist  preparations.  Colonel 
Woodward,  of  Washington,  uses  a  solution  of  dried  or 
evaporated  Canada  balsam  in  chloroform  or  benzole. 

Dammar  Varnish. — Dr.  Klein  and  other  German  his- 
tologists  prefers  this  to  Canada  balsam.  Dissolve  J  to  1 
ounce  of  gum  Dammar  in  1  ounce  of  turpentine ;  also  } 
to  1  ounce  of  mastic  in  2  ounces  of  chloroform.  Mix  and 
filter. 

Glycerin. — This  fluid  is  universally  useful  to  the  micros- 
copist.  (See  Preparation  in  Viscid  Media,  page  65.)  Vege- 
table and  animal  substances  may  be  preserved  in  glycerin, 
but  if  it  is  diluted,  camphor  or  creasote  must  be  added 
to  prevent  confervoid  growths.  It  is  said,  however,  to 
dissolve  carbonate  of  lime. 

Gelatin  and  Glycerin. — Soak  gelatin  in  cold  water  till 
soft,  then  melt  in  warm  water,  and  add  an  equal  quantity 
of  glycerin. 

Gum  and  Glycerin. — Dissolve  1J  grains  of  arsenious 
acid  in  1  ounce  of  water,  then  1  ounce  of  pure  gum  arabic 
(without  heat),  and  add  1  ounce  of  glycerin. 

Deane's  Compound. — Soak  1  ounce  of  gelatin  in  5  ounces 
of  water  till  soft ;  add  5  ounces  of  honey  at  a  boiling  heat. 
Boil  the  mixture,  and  when  cool,  add  ti  drops  of  creasote 
in  |  ounce  of  alcohol;  filter  through  flannel.  To  be  used 
warm. 

Carbolic  Acid. — 1 : 100  of  water  is  a  good  preservative. 

Thwaite's  Fluid.— To  16  parts  of  distilled  water,  add  1 
part  of  rectified  spirit  and  a  few  drops  of  creasote ;  stir  in 
a  little  prepared  chalk,  and  filter.  Mix  an  equal  measure 
of  camphor-water,  and  strain  before  using.  For  preserva- 
tion of  algse. 

Solution  of  Naphtha  and  Creasote. — Mix  3  drachms  of 
creasote  with  6  ounces  of  wood  naphtha ;  make  a  thick, 
smooth  paste  with  prepared  chalk,  and  add  gradually, 
rubbing  in  a  mortar,  64  ounces  of  water.  Add  a  few 
lumps  of  camphor,  and  let  it  stand  several  weeks  before 


MODERN  METHODS  OP  EXAMINATION.        75 

pouring  off  or  filtering  the  clear  fluid.  Dr.  Beale  recom- 
mends this  highly  for  the  preservation  of  dissections  of 
nerves  and  morbid  specimens. 

Ealfs  Fluid.— As  a  substitute  for  Thwaite's  fluid  in 
the  preservation  of  algae.  1  grain  of  alum  and  1  of  bay 
salt  to  1  ounce  of  distilled  water. 

Goadby's  Solution. — Bay  salt,  4  ounces;  alum, 2  ounces; 
corrosive  sublimate,  4  grains ;  boiling  water,  4  pints. 
This  is  the  strength  most  generally  useful,  although  it 
may  be  made  stronger  or  more  dilute.  It  is  a  useful 
fluid.  If  the  specimen  contain  carbonate  of  lime,  the 
alum  must  be  left  out,  and  the  quantity  of  salt  may  be 
quadrupled. 

Dr.  Beale  discards  all  solutions  containing  salts  for 
microscopic  purposes,  as  they  render  the  textures  opaque 
and  granular. 

Soluble  Glass,  or  a  solution  of  silicate  of  soda  or  potash, 
or  of  both,  has  been  proposed,  but  it  is  apt  to  render 
specimens  opaque. 

Chloride  of  Calcium  in  saturated  aqueous  solution  has 
been  much  recommended,  especially  by  botanists. 

Acetate  of  Potash,  a  nearly  saturated  solution,  is  useful 
for  vegetable  preparations  and  for  specimens  of  animal 
tissue  which  have  been  stained  with  osmic  acid.  The 
latter  do  not  bear  glycerin. 

Pacinian  Fluid.— This  is  variously  modified,  but  may 
consist  of  corrosive  sublimate,  1  part ;  chloride  of  sodium, 
2  parts;  glycerin,  13  parts;  distilled  water,  113  parts. 
Sometimes  acetic  acid  is  substituted  for  chloride  of  so- 
dium. 

6.  CEMENTS. 

Gold  Size  is  recommended  by  Dr.  Carpenter  as  most 
generally  useful  for  thin  covers.  It  is  made  by  boiling 
25  parts  of  linseed  oil  for  three  hours  with  1  part  of  red 
lead  and  J  of  as  much  umber.  The  fluid  part  is  then 
mixed  with  yellow  ochre  and  white  lead  in  equal  parts, 


76  THE    MICROSCOPIST. 

so  as  to  thicken  it,  the  whole  boiled  again,  and  the  fluid 
poured  off  for  use. 

Bell's  Cement  is  said  to  be  best  for  glycerin  specimens. 
It  appears  to  be  shellac  dissolved  in  strong  alcohol. 

Brunswick  Black  is  asphaltum  dissolved  in  turpentine. 
A  little  india-rubber  dissolved  in  mineral  naphtha  is  some- 
times added. 

Canada  Balsam  in  chloroform  or  Dammar  varnish  (page 
74)  is  often  used  as  a  cement. 

Marine  Glue. — This  is  most  useful  in  building  glass 
cells,  etc.  It  consists  of  equal  parts  of  shellac  and  india- 
rubber  dissolved  in  mineral  naphtha  by  means  of  heat. 

Electrical  Cement  is  made  by  melting  together  5  parts 
of  rosin,  1  of  beeswax,  and  1  of  red  ochre.  2  parts  of 
Canada  balsam  added  make  it  more  adhesive  to  glass. 

White,  hard  Varnish,  or  gum  sandarac,  dissolved  in 
alcohol  and  mixed  with  turpentine  varnish,  is  sometimes 
colored  by  lampblack,  sealing-wax,  etc. 

White  Zinc  Cement. — Oxide  of  zinc  rubbed  up  with 
equal  parts  of  oil  of  turpentine  and  8  parts  of  solution  of 
gum  Dammar  in  turpentine  of  a  syrupy  consistence,  or 
Canada  balsam,  chloroform,  and  oxide  of  zinc. 


CHAPTER   VI. 

MOUNTING    AND   PRESERVING   OBJECTS    FOR    THE   MICROSCOPE. 

FOR  the  permanent  preservation  of  specimens,  various 
means  are  employed,  according  to  the  nature  of  the  object 
and  the  particular  line  of  investigation  desired.  Few,  if 
any,  objects  show  all  their  peculiarities  of  structure  or 
adaptation  to  function,  and  for  scientific  work  it  is  often 


MOUNTING    AND    PRESERVING    OBJECTS.  77 

necessary  to  have  the  same  structure  prepared  in  different 
ways. 

Opaque  Objects  have  sometimes  been  attached  by  thick 
gum  to  small  disks  of  paper,  etc  ,  or  to  the  bottom  and 
sides  of  small  pill-boxes,  or  in  cavities  in  slides  of  bone  or 
wood,  but  they  are  better  preserved  on  glass  slides,  as 
hereafter  described. 

The  most  convenient  form  of  slide  for  microscopic  pur- 
poses is  made  of  flattened  crown  or  flint  glass,  cut  into 
slips  of  three  inches  by  one  inch,  and  ground  at  the  edges. 
Some  preparations  are  mounted  on  smaller  slips,  but  they 
are  less  convenient  than  the  above,  which  is  regarded  as 
the  standard  size. 

On  such  slides  objects  are  fixed,  and  covered  by  a  square 
or  round  piece  of  thin  glass,  varying  from  g^th  to  2J5th 
of  an  inch  in  thickness.  Both  slides  and  thin  glass  can 
be  procured  at  opticians'  stores.  Laminae  of  mica  or  talc 
are  sometimes  used  for  lack  of  better  material,  but  are  too 
soft.  For  object-glasses  of  the  shortest  focal  length,  how- 
ever, it  is  necessary  at  times  to  resort  to  this  sort  of  cov- 
ering. 

Great  care  should  be  taken  to  have  both  slide  and  cover 
clean.  With  thin  glass  this  is  difficult,  owing  to  its  brit- 
tleness.  Practice  will  teach  much,  but  for  the  thinnest 
glass  two  flat  pieces  of  wood  covered  with  chamois  leather, 
between  which  the  cover  may  lie  flat  as  it  is  rubbed;  will 
be  serviceable. 

Very  thin  specimens  may  be  mounted  in  balsam,  glyc- 
erin, etc.,  covered  with  the  thin  glass  cover,  and  then 
secured  by  a  careful  application  of  cement  to  the  edges  of 
the  cover.  If,  however,  the  pressure  of  the  thin  glass  be 
objectionable,  or  the  object  be  of  moderate  thickness,  some 
sort  of  cell  should  be  constructed  on  the  slide. 

The  thinnest  cells  are  made  with  cement,  as  gold  size, 
Brunswick  black^ etc.,  painted  on  with  a  camel's-hair  pen- 
cil. For  preparing  these  with  elegance,  Shadbolt's  turn- 


78 


THE    MICROSCOPIST. 


table  has  been  contrived  (Fig.  36).  The  slide  is  placed 
between  the  springs,  and  while  rotated,  a  ring  of  varnish 
of  suitable  breadth  is  made  on  the  glass. 

A  piece  of  thin  glass  (or  even  of  thick  glass)  may  be 
perforated  and  cemented  to  the  slide  with  marine  glue  by 


FIG. 


Shadbolt's  Turntable  for  making  Cement-Cells. 

the  aid  of  heat;  or  vulcanite,  lead,  tin,  gutta  percha,  etc., 
may  be  made  into  a  cell  in  a  similar  way  as  seen  in  Fig. 
37. 

The  perforation  of  thin  glass  may  be  easily  performed 
by  cementing  it  over  a  hole  in  a  brass  plate,  etc.,  with 
marine  glue,  and  punching  it  through  with  the  end  of  a 


FIG.  37. 


Cell  of  Glass,  Vulcanite,  etc. 

file.  The  edges  may  then  be  filed  to  the  size  of  the  hole, 
and  the  glass  removed  by  heating  the  brass.  Thicker 
glass  may  be  bored  with  a  file  by  moistening  it  with 
turpentine. 

Dry  objects,  especially  if  they  are  transparent,  as  dia- 
toms, thin  sections  of  bone,  crystals,  etc.,  may  be  attached 
to  the  slide  with  Canada  balsam,  etc.,  covered  with  thin 


MOUNTING    AND    PRESERVING    OBJECTS.  79 

glass,  which  should  be  cemented  at  the  edges,  and  gummed 
over  all  a  strip  of  colored  or  lithographed  paper,  in  which 
an  aperture  has  been  made  with  a  punch. 

Mounting  in  Balsam,  or  Dammar  Varnish  is  suitable  for 
a  very  large  proportion  of  objects.  It  increases  the  trans- 
parency of  many  structures,  tilling  up  interstices  and  cavi- 
ties, and  giving  them  a  smooth,  beautiful  appearance. 
Very  delicate  tissues,  as  fine  nerves,  etc.,  are  rendered  in- 
visible by  it,  and  require  other  fluids,  as  glycerin. 

Before  mounting  in  balsam,  the  object  should  be  thor- 
oughly dry,  otherwise  a  milky  appearance  will  result.  It 
should  then  be  placed  in  oil  of  cloves  or  of  turpentine  to 
remove  greasiness  and  increase  the  transparency.  A  clean 
slide,  warmed  over  a  spirit-lamp  or  on  a  hot  plate,  should 
then  have  a  little  balsam  placed  on  its  centre,  and  the 
object  carefully  lifted  from  the  turpentine  is  put  into  the 
balsam  and  covered  with  another  drop.  The  slide  should 
then  be  gently  warmed,  and  any  air-bubbles  pricked  with 
a  needle-point  or  drawn  aside.  The  thin  glass  cover  should 
be  warmed  and  put  on  gently,  in  such  a  way  as  to  lean 
first  on  one  edge  and  fall  gradually  to  a  horizontal  posi- 
tion. The  slide  may  be  warmed  again,  and  the  superflu- 
ous balsam  pressed  from  under  the  cover  by  the  pressure 
of  a  clean  point  upon  it. 

If  the  object  is  full  of  large  air-spaces  and  is  not  likely 
to  be  injured  by  heat,  the  air  may  be  expelled  by  gently 
boiling  it  in  the  balsam  on  the  slide.  If  the  object  be  one 
which  will  curl  up,  or  is  otherwise  injured  by  heat,  the 
air-pump  must  be  resorted  to.  A  cheap  substitute  for  the 
air-pump  may  be  made  by  fitting  a  piston  into  a  tolerably 
wide  glass  tube  closed  at  one  end.  The  piston  should 
have  a  valve  opening  outwards.  The  preparation  in  bal- 
sam may  be  placed  at  the  bottom  of  the  tube,  and  a  few 
strokes  of  the  piston  will  exhaust  the  air. 

To  fill  a  deep  cell  with  Canada  balsam,  it  may  be  well 
to  fill  it  first  with  turpentine  and  place  the  specimen  in 


80  THE    MICROSCOPIST. 

it.  Then  pour  in  the  balsam  at  one  end,  the  slide  being 
inclined  so  that  the  turpentine  may  run  out  at  the  other. 
Lay  the  cover  on  one  edge  of  the  cell  and  gradually  lower 
it  till  it  lies  flat.  In  this  way  air  may  be  excluded. 

The  solution  of  balsam  in  chloroform  needs  no  heat, 
and  has  little  liability  of  air-bubbles. 

The  excess  of  balsam  round  the  edge  of  the  glass  cover 
may  be  removed  with  a  knife  and  cleaned  with  turpentine 
or  benzine,  etc. 

For  animal  tissues,  the  oil  of  cloves  is  sometimes  used 
instead  of  turpentine  to  increase  the  transparency,  and  a 
wet  preparation,  as  a  stained  or  injected  specimen,  may 
be  mounted  in  balsam  or  Dammar  by  first  placing  it  in 
absolute  alcohol  to  extract  the  water,  then  transferring 
to  oil  of  cloves  or  turpentine,  and  lastly,  to  the  balsam. 
In  a  reverse  order,  a  specimen  from  balsam  may  be  cleaned 
and  mounted  in  fluid. 

Mounting  in  Fluid  is  necessary  for  the  preservation  of 
the  most  delicate  tissues  and  such  as  may  be  injured  by 

FIG.  38. 


Spring  Clip. 

drying.  Glycerin  is  perhaps  the  most  generally  useful 
fluid.  (See  Preservative  Fluids,  page  73.) 

For  mounting  in  fluid,  it  is  safer  to  have  a  thin  cell  of 
varnish  prepared  first  than  to  risk  the  running  in  of  the 
cement  under  the  cover,  as  will  be  likely  to  occur  other- 
wise. 

The  air-pump  is  sometimes  needed  in  mounting  in  fluid 
to  get  rid  of  air-bubbles.  A  spring  clip  (Fig.  38)  is  also 


MOUNTING    AND    PRESERVING    OBJECTS.  81 

a  useful  instrument  for  making  moderate  pressure  on  the 
glass  cover  until  the  cement  on  its  edge  is  dry.  A  drop- 
ping-tube  with  a  bulbous  funnel,  covered  with  thin  india- 
rubber,  for  taking  up  and  dropping  small  quantities  of 
fluid,  wrill  also  be  of  service. 

Superfluous  fluid  may  be  removed  from  the  edge  of  the 
cover  by  a  piece  of  blotting-paper,  care  being  used  not  to 
draw  away  the  fluid  beneath  the  cover. 

As  soon  as  objects  are  mounted,  the  slides  should  be 
labelled  before  cementing  is  finished,  otherwise  time  will 
be  lost  in  searching  for  a  particular  object  among  others, 
or  the  name  may  be  forgotten. 

Boxes  of  wood  or  of  pasteboard,  with  grooved  racks  at 
the  sides,  are  occasionally  used  for  preserving  a  collection 
of  specimens.  It  is  better,  however,  to  have  a  cabinet 
with  drawers  or  trays  so  that  the  specimens  may  lie  flat, 
with  their  ends  towards  the  front  of  the  drawer.  A  piece 
of  porcelain  on  the  end  of  the  drawer  is  convenient  for 
the  name  of  the  class  of  objects  contained,  to  be  written 
on  with  lead-pencil. 

Collecting  Objects. — The  methods  pursued  by  naturalists 
generally  will  suffice  for  a  large  proportion  of  the  objects 
which  are  matters  of  microscopic  inquiry,  but  there  are 
others  wrhich,  from  their  minuteness,  require  special  search. 
Many  fresh-water  species  of  microscopic  organisms  inhabit 
pools,  ditches,  and  streams.  Some  attach  themselves  to 
the  stems  and  leaves  of  aquatic  plants,  or  to  floating  and 
decaying  sticks,  etc.  Others  live  in  the  muddy  sediment 
at  the  bottom  of  the  water.  A  pond  stick  has  been  con- 
trived for  the  collection  of  such  organisms,  consisting  of 
two  lengths,  sliding  one  within  the  other,  so  that  it  may 
be  used  as  a  walking-cane.  In  a  screw  socket  at  one  end 
may  be  placed  a  curved  knife  for  cutting  portions  of  plants 
which  contain  microscopic  parasites;  or  a  screw  collar  for 
carrying  a  screw-topped  bottle,  which  serves  to  bring  up 
a  sample  of  liquid ;  or  it  may  have  a  ring  for  a  muslin  net. 


82  THE    MICROSCOPIST. 

The  net  should  be  confined  by  an  india-rubber  band  in  a 
groove,  so  as  to  be  slipped  off  readily  and  emptied  into  a 
bottle.  The  collector  should  have  enough  bottles  to  keep 
organisms  from  each  locality  separate,  and  when  animal- 
cules are  secured  enough,  air  should  be  left  to  insure  their 
safety. 

Marine  organisms  may  be  obtained  in  a  similar  way  if 
they  inhabit  the  neighborhood  of  the  shore,  but  others 
can  only  be  secured  by  means  of  the  dredge  or  tow-net. 
The  latter  may  be  of  fine  muslin  sewn  to  a  wire  ring  of 
twelve  inches  diameter.  It  may  be  fastened  with  strings 
to  the  stern  of  a  boat,  or  held  by  a  stick  so  as  to  project 
from  the  side.  For  the  more  delicate  organisms,  the  boat 
should  be  rowed  slowly,  so  that  the  net  may  move  gently 
through  the  water.  Firmer  structures  may  be  obtained 
by  attaching  a  wide-mouthed  bottle  to  the  end  of  a  net 
made  conical,  and  double,  so  that  the  inner  cone  may  act 
as  a  valve.  The  bottle  may  be  kept  from  sinking  by  a 
piece  of  cork.  Such  a  net  may  be  fixed  to  the  stern  of  a 
vessel,  and  drawn  up  from  time  to  time  for  examination. 

Minute  organisms  may  be  examined  on  the  spot  by 
fishing  them  out  of  the  bottle  with  a  pipette,  or  small 
glass  tube,  and  placing  them  on  a  slide.  A  Coddington 
or  other  pocket  lens  will  suffice  to  show  which  are  desir- 
able for  preservation. 

Many  of  the  lower  animals  and  plants  may  be  kept 
alive  in  glass  jars  for  some  time.  Frogs,  etc.,  may  be 
kept  under  wire  covers  with  a  large  piece  of  moist  sponge. 

Aquaria  of  various  sorts  may  be  procured  and  stocked 
at  small  expense,  and  will  afford  a  constant  source  of  in- 
struction. For  fresh-water  aquaria  the  bottom  of  the  jar, 
etc  ,  should  be  covered  with  rich  black  earth,  made  into 
a  paste,  and  this  should  be  surmounted  with  a  layer  of 
fine  washed  sand.  Roots  of  Valisneria,  Anacharis,  or 
Ckara  may  then  be  planted  in  the  earth  and  the  vessel 
filled  with  water.  As  soon  as  the  water  is  clear,  put  a 


MOUNTING    AND    PRESERVING    OBJECTS. 

few  fresh-water  molluscs  in  to  keep  clown  the  growth  of 
confervse,  especially  such  as  feed  on  decayed  vegetable 
matter,  as  Planorbis  carinatus,  Paludina  vivipara,  or  Am- 
phibia glutinosa.  When  bubbles  of  oxygen  gas  appear,, 
fish,  water  insects,  etc.,  may  be  introduced. 

Marine  aquaria  require  more  skill  than  those  for  fresh 
water,  but  for  temporary  purposes,  the  plan  described  by 
Mr.  Highley,  in  Dr.  Beale's  How  to  Work  with  the.  Micro- 
scope, is  excellent.  He  fills  a  number  of  German  beaker 
glasses  with  fresh  sea-water,  and  places  them  in  a  sunny 
window.  He  then  drops  in  each  one  or  two  limpet  shells- 
from  which  the  animals  have  been  removed,  and  upon 
which  small  plants  of  Enteromorpha  and  Ulva  are  growing. 
In  a  short  time  the  sides  of  the  jars  next  the  light  become 
coated  with  spores.  He  keeps  the  other  sides  clean  with 
a  piece  of  wood  or  sponge,  so  as  to  observe  the  small 
marine  animals  which  may  now  be  placed  in  the  beakers. 
In  this  way  a  collection  will  keep  healthy  for  months. 
After  the  sides  are  covered  with  spores,  the  sea-weeds 
may  be  removed,  and  the  jars  placed  on  a  table  at  such  a 
distance  from  the  window  that  the  light  impinges  only 
on  the  coated  half,  taking  care  that  there  is  sufficient  light 
to  stimulate  the  spores  to  throw  off  bubbles  of  oxygen 
daily. 

Prawns,  fish,  actiniae,  etc.,  may  be  fed  on  shreds  of  beef 
which  has  been  pounded  and  dried,  and  then  macerated 
in  sea-water  for  a  few  minutes.  All  dead  animals,  slime, 
or  effete  matter  should  be  removed  by  wooden  forceps, 
etc  ,  as  soon  as  noticed. 


84  THE    MICROSCOPIST. 

CHAPTER   VII. 

THE    MICROSCOPE   IN   MINERALOGY    AND   GEOLOGY. 

MICROSCOPIC  examination  of  minute  fossil  organisms,  as 
Diatoms,  Foraminifera,  spicules  of  sponge,  etc.,  has  long 
been  a  subject  of  interest.  Latterly,  however,  the  micro- 
scope has  been  found  to  be  essential  to  the  study  of  phys- 
ical geology  and  petrology.  How  many  crude  and  verbose 
theories  respecting  cosmogony  will  disappear  by  this  means 
of  investigation  time  must  reveal,  but  the  animal  nature 
of  the  Eozoon  Canadense  found  in  the  Serpentine  Lime- 
stone of  the  Lauren tian  formation  of  Canada,  parallel  with 
the  Fundamental  Gneiss  of  Europe,  and  the  discovery  by 
Mr.  Sorby*  of  minute  cavities  filled  with  fluid  in  quartz 
and  volcanic  rocks,  are  indications  that  speculations  based 
upon  a  merely  external  or  even  chemical  examination  of 
rock  structures  are  immature  and  inadequate. 

The  systematic  study  of  microscopic  mineralogy  and 
geology  will  require  a  large  outlay  of  time  and  patience, 
and  the  field  is  one  which  is  scarcely  trodden.  The  plan 
of  this  work  will  only  permit  a  brief  outline,  sufficient  to 
aid  a  beginner,  and  indicating  the  value  and  the  methods 
of  minute  investigation. 

Preparation  of  Specimens. — Examination  of  the  outer 
surface  of  a  mineral  specimen,  viewed  as  an  opaque  body 
with  a  low  power  and  by  condensed  light,  is  sometimes 
useful.  The  metals  and  their  alloys,  with  most  of  their 
combinations  with  sulphur,  etc  ,  admit  of  no  other  method. 
Occasionally,  as  in  iron  and  steel,  the  microscopic  structure 
is  best  seen  by  polishing  the  surface,  and  then  allowing 
the  action  of  very  dilute  nitric  acid.  Mr.  Forbesf  states 

*  See  Beale's  How  to  Work  with  the  Microscope. 

f  The  Microscope  in  Geology,  Popular  Science  Review,  No.  25. 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.       85 

that  many  vitreous  specimens  (quite  transparent)  show  no 
trace  of  structure  until  the  surface  has  been  carefully  acted 
on  by  hydrofluoric  acid. 

It  is  generally  necessary  to  have  the  specimens  flat  and 
smooth,  and  thin  enough  to  transmit  light.  Sometimes 
fragments  may  be  thin  enough  to  show  structure  when 
mounted  in  balsam,  as  in  the  case  of  quartz,  obsidian,  pitch- 
stone,  etc.,  but  usually  thin  sections  must  be  ground  and 
polished. 

Chip  off  a  fragment  of  the  rock  as  flat  and  thin  as  pos- 
sible, or  cut  with  a  lapidary's  wheel,  or  a  toothless  saw  of 
sheet-iron  with  emery.  Grind  down  the  specimen  on  an 
iron  or  pewter  plate 'in  a  lathe  until  perfectly  flat.  Then 
grind  with  finer  emery  on  a  slab  of  fine-grained  marble  or 
slate,  and  finish  with  water  on  a  fine  hone,  avoiding  all 
polishing  powders  or  oil.  When. perfectly  smooth,  cement 
the  specimen  on  a  square  of  glass  with  Canada  balsam, 
and  grind  the  other  side  until  as  thin  as  necessary,  finish 
as  before,  remove  it  from  the  glass,  and  mount  on  a  glass 
slide  in  balsam. 

In  this  way,  most  silicates,  chlorides,  fluorides,  carbo- 
nates, sulphates,  borates,  many  oxides,  sulphides,  etc.,  may 
be  prepared  for  examination  by  transmitted  light.  Very 
soft  rocks  may  be  soaked  in  turpentine,  then  in  soft  balsam, 
and  afterwards  heated  until  quite  hard.  The  deep  scratches 
on  hard  minerals,  like  quartz,  left  by  the  use  of  coarse 
emery,  may  be  removed  by  using  fine  emery  paper  held 
flat  on  a  piece  of  plate  glass,  and  finally  polished  with 
rouge  on  parchment.  Perhaps  oxide  of  chromium  from 
its  hardness  will  be  found  the  best  polishing  material. 
Crystals  of  soluble  salts  may  be  ground  on  emery  paper 
and  polished  with  rouge.  Sometimes  much  may  be  learned 
by  acting  on  one  side  only  of  a  specimen  with  dilute  acid. 

Examination  of  Specimens. — The  object  of  microscopic 
examination  of  minerals  is  to  determine  not  only  the  nature 
of  the  material  of  which  they  are  composed,  but  also,  and 


86  THE    MICROSCOPIST. 

chiefly,  their  structure,  whether  homogeneous,  derived 
from  the  debris  of  previous  rocks,  or  from  the  agency  of  the 
organic  world.  Ordinary  mineral ogical  characteristics,  as 
to  hardness,  specific  gravity,  color,  lustre,  form,  cleavage, 
and  fusibility,  and  above  all,  chemical  composition,  may 
•suffice  to  show  the  material,  but  the  microscope  will  give 
valuable  assistance  to  this  end,  and  is  essential  to  a  knowl- 
edge of  structure. 

Crystalline  Forms. — The  laws  of  crystallography  teach 
that  each  chemical  combination  corresponds  to  a  distinct 
relation  of  all  the  angles  which  can  possibly  arise  from 
the  primary  form,  so  that  the  angular  inclination  of  the 
facets  of  a  crystal  is  a  question  of  importance.  This  can 
be  ascertained  by  a  microscope  having  a  revolving  stage, 
properly  graduated,  or  by  the  use  of  a  goniometer,  which 
is  a  thread  stretched  across  the  focus  of  the  eye-lens,  and 
attached  to  a  movable  graduated  circle  and  vernier.  The 
eye  piece  attached  to  the  polariscope  of  Hartnack  is  thus 
arranged,  so  as  to  act  also  as  a  goniometer. 

Crystals  are  assumed  to  possess  certain  axes,  and  the 
form  is  determined  by  the  relation  of  the  plane  surface  to 
these  axes.  Although  the  forms  of  crystals  are  almost 
infinitely  varied,  they  may  be  classified  into  seven  crystal- 
lographic  systems. 

1.  The  Regular  Cubic  or  Monometric  System  (Fig.  39). — 
These  crystals  are  symmetrical,  about  three  rectangular 
axes.     The  simplest  forms  are  the  cube  and  octahedron. 
Examples,  diamond,  most  metals,  chloride  of  sodium,  fluor 
spar,  alum. 

2.  The  Quadratic  or  Dimetric  System  (Fig.  40). — Crystals 
symmetrical,  about  three  rectangular  axes,  but  only  two 
axes  of  equal  length.     Examples,  sulphate  of  nickel,  tung- 
state  of  lead,  and  double  chloride  of  potassium  and  cop- 
per. 

3.  Hexagonal  or  Rhombohedral  System  (Fig.  41). — Crys- 
tals with  four  axes ;  three  equal  in  length,  in  one  plane, 


FIG.  39. 


Principal  or  Vertical  Axes.  Secondary  or  Lateral  Axes, 

FIG.  41. 


Principal  Axes.  Secondary  Axes. 

FIG.  42. 


Principal  Axes,  Secondary  Axes. 

FIG.  43. 


Principal  Axes.  Secondary  Axes. 

FIG.  44. 


Principal  Axes. 


Secondary  Axes. 


88  THE    MICROSCOPIST. 

and  inclined  60°  to  each  other,  and  a  principal  axis  at 
right  angles  to  the  plane  of  the  others.  Examples,  quartz, 
beryl,  and  calc-spar. 

4.  RhomJbic  or  Trimetric  System  (Fig.  42). — Three  rec- 
tangular axes,  all  of  different  lengths.    Examples,  sulphate 
of  potassium,  nitrate  of  potassium,  sulphate  of  barium, 
and  sulphate  of  magnesium. 

5.  Oblique  Prismatic  or  Monodinic  (Fig.  43). — Two  axes 
obliquely  inclined,  and  a  third  at  right  angles  to  the  plane 
of  these  two ;  all  three  being  unequal.     Examples,  ferrous 
sulphate,  sugar,  gypsum,  and  tartaric  acid. 

6.  Diclinic  System. — Two  axes  at  right  angles,  and  a 
third  oblique  to  the  plane  of  these ;    the  primary  form 
being  a  symmetrical  eight  sided  pyramid. 

7.  Doubly  Oblique  Prismatic  or  Triclinic  (Fig.  44). — Three 
axes  all  inclined  obliquely  and  of  equal  length.     Example, 
sulphate  of  copper. 

Crystalline  structure  being  inherent  in  the  nature  of 
the  mineral,  becomes  perceptible  by  the  manner  of  divi- 
sion. A  slight  blovv  on  a  piece  of  calc-spar  will  separate 
it  into  small  rhombohedrons  or  parallelopipeds,  or  produce 
internal  fissures  along  the  planes  of  cleavage,  which  will 
suffice  to  determine  their  angles. 

Crystals  are  often  found  in  groups,  with  various  modes 
of  arrangement.  Cubes  are  sometimes  aggregated  so  as 
to  form  octahedra,  and  prismatic  crystals  are  often  united 
together  at  one  extremity.  But  the  most  singular  groups 
are  those  called  hemitropes,  because  they  resemble  a  crys- 
tal cut  in  two,  with  one  part  turned  half  round  and  re- 
united to  the  other. 

In  all  the  numerous  forms,  however,  we  find  in  the  same 
species  the  same  angles  or  inclination  of  planes,  although 
the  unequal  size  of  the  faces  may  lead  to  great  apparent 
irregularity,  as  in  distorted  crystals  of  quartz,  where  one 
face  of  the  pyramid  is  enlarged  at  the  expense  of  the  rest. 


THE    MICEOSCOPE    IN    MINERALOGY    AND    GEOLOGY.      89 

An  apparent  distortion  may  also  be  produced  by  an  oblique 
section. 

The  following  examples  may  be  of  service,  as  showing 
the  value  of  angular  measurement  in  minerals: 

Quartz.  Rhombohedral  system.  Inclination  of  two 
adjoining  faces  94°  15'. 

Felspar.     Monoclinic.     Cleavage  planes  at  right  angles. 

Albite  or  soda  felspar.     Triclinic.     Angle  93°  36'. 

Mica.     Oblique  prisms. 

Magnesian  mica.    Right,  rhombic,  or  hexagonal  prisms. 

Garnet.     Dodecahedrons  or  trapezohedrons. 

Idocrase.     Square  prisms. 

Epidote.     Oblique  prisms. 

Scapolite.     Square  and  octagonal  prisms. 

Andalusite.     Prisms  of  90°  44'. 

Staurotide.     Rhombic  prisms  of  129°  20'. 

Tourmaline.     Three,  six,  nine,  or  twelve-sided  prisms. 

Topaz.     Rhombic  prisms  of  124°  19'. 

Beryl.     Six-sided  prisms. 

Hornblende.     Monoclinic.     124°  30'. 

Augite  or  pyroxene.     Monoclinic.     87°  5'. 

Calcite  or  carbonate  of  lime.  Forms  various,  but  105° 
5'  between  the  cleavage  faces. 

Magnesite.     Angle  107°  29'. 

Dolomite.     106°  15'. 

Gypsum.     Monoclinic. 

Crystals  within  Crystals. — Many  specimens  which  appear 
perfectly  homogeneous  to  the  naked  eye  are  shown  by  the 
microscope  to  be  very  complex.  The  minerals  of  erupted 
lavas  are  often  full  of  minute  crystals,  leading  to  very 
anomalous  results  of  chemical  analysis.  Some  care  is 
needed  at  times  to  distinguish  such  included  minerals 
from  cavities  filled  with  fluid.  The  use  of  polarized  light 
will  sometimes  determine  this  point. 

Cavities  in  Crystals. — Mr.  Sorby  has  shown  that  the 
various  cavities  in  minerals  containing  air,  water,  glass, 


90  THE    MICKOSCOPIST. 

or  stone  will  often  indicate  under  what  conditions  the 
rock  was  formed.  Thus  crystals  with  water  cavities  were 
formed  from  solution  ;  those  with  stone  or  glass  cavities 
from  igneous  fusion ;  those  with  both  kinds  by  the  com- 
bined influence  of  highly  heated  water  and  melted  rock 
under  great  pressure ;  while  those  that  contain  no  cavi- 
ties were  formed  very  slowly,  or  from  the  fusion  of  homo- 
geneous substance. 

Use  of  Polarized  Light. — Mr.  Sorby  states  that  the 
action  of  crystals  on  polarized  light  is  due  to  their  double 
refraction,  which  depolarizes  the  polarized  beam,  and 
gives  rise  to  colors  by  interference  if  the  crystal  be  not 
too  thick  in  proportion  to  the  intensity  of  its  power  of 
double  refraction.  This  varies  much,  according  to  the 
position  in  which  the  crystal  is  cut,  yet  we  may  form  a 
general  opinion,  since  it  is  the  intensity  and  not  the  char- 
acter of  the  depolarized  light  which  varies  according  to 
the  position  of  the  crystal.  There  are  two  axes  at  right 
angles  to  each  other,  and  when  either  of  them  is  parallel 
to  the  plane  of  polarization,  the  crystal  has  no  depolariz- 
ing action,  and  if  the  polarizing  and  analyzing  prisms  are 
crossed,  it  looks  black.  On  rotating  the  crystal  or  the 
plane  of  polarization,  the  intensity  of  depolarizing  action 
increases  until  the  axes  are  at  45°,  and  then  diminishes 
till  the  other  axis  is  in  the  plane.  If,  therefore,  this  takes 
place  uniformly  over  a  specimen,  we  know  that  it  has  one 
simple  crystalline  structure,  but  if  it  breaks  up  into  de- 
tached parts,  we  know  it  is  made  up  of  a  number  of  sepa- 
rate crystalline  portions. 

The  definite  order  that  may  occur  in  the  arrangement 
of  a  number  of  crystals  may  indicate  important  differences. 
Some  round  bodies,  for  example,  like  oolitic  grains,  have 
been  formed  by  crystals  radiating  from  a  common  nu- 
cleus ;  whilst  others,  as  in  meteorites,  have  the  structure 
of  round  bodies  which  crystallized  afterwards. 

Sir  .D.  Brewster  discovered  that  many  crystals  have 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.       91 

two  axes  of  double  refraction,  or  rather  axes  around  which 
double  refraction  occurs.  Thus  nitre  crystallizes  in  six- 
sided  prisms,  with  angles  of  about  120°.  It  has  two  axes 
of  double  refraction  inclined  about  2J°  to  the  axes  of  the 
prism,  and  5°  to  each  other,  so  that  a  piece  cut  from  such 
a  crystal  perpendicular  to  the  axes,  shows  a  double  system 
of  rings  when  a  ray  of  polarized  light  is  transmitted. 
When  the  line  connecting  the  axes  is  inclined  45°  to  the 
plane  of  polarization,  a  cross  is  seen,  which  gradually 
assumes  the  form  of  two  hyperbolic  curves  on  rotating 
the  specimen  If  the  analyzer  be  revolved,  the  black  cross 
will  be  replaced  by  white,  the  red  rings'  by  green,  the  yel- 
low by  indigo,  etc.  These  rings  have  the  same  colors  as 
thin  plates,  or  a  system  of  rings  round  one  axis.  Mica 
has  two  sets  of  rings,  with  the  angle  between  the  axes  of 
60°  to  75°.  Magnesian  mica  gives  an  angle  of  5°  to  20°. 
Determination  of  the  Origin  of  Rock  Specimens. — Mr. 
Forbes  has  shown  that  the  primary  or  eruptive  rocks, 
consisting  chiefly  of  crystallized  silicates,  with  small 
quantities  of  other  minerals,  are  developed  as  more  or 
less  perfect  crystals  at  all  angles  to  one  another,  indicat- 
ing the  fluid  state  of  the  mass  at  some  previous  time. 
The  secondary  or  sedimentary  rocks  consist  of  rocks 
formed  by  the  immediate  products  of  the  breaking  up  of 
eruptive  rocks,  or  are  built  of  the  debris  of  previous  erup- 
tive or  sedimentary  rocks,  or  composed  of  extracts  from 
aqueous  solution  by  crystallization,  precipitation,  or  the 
action  of  organic  life.  The  accompanying  figures,  selected 
from  Mr.  Forbes's  article  in  the  Popular  Science  Review, 
well  illustrate  this  method  of  investigation.  Plate  II, 
Fig.  45,  is  a  section  of  lava  from  Vesuvius,  magnified 
twrelve  diameters,  showing  crystals  of  augite  in  a  hard 
gray  rock.  Plate  II,  Fig.  46,  is  a  volcanic  rock  from 
Tahiti,  consisting  of  felspar,  with  olivine  and  magnetic 
oxide  of  iron,  and  numerous  crystals  of  a  pyroxenic  min- 
eral. Plate  II,  Fig.  47,  is  pitchstone  from  a  dyke  in  new 


92  THE    MICROSCOPIST. 

red  sandstone,  magnified  seventy-five  diameters.  Exter- 
nally it  resembles  dirty  green  bottle-glass,  but  shows  in 
the  microscope  an  arborescent  crystallization  of  a  green 
pyroxenic  mineral  in  a  colorless  felspar  base.  Plate  II, 
Fig.  48,  shows  auriferous  diorite  from  Chili,  consisting  of 
felspar,  with  hornblende  and  crystals  of  iron  pyrites,  mag- 
nified thirty  diameters.  Plate  II,  Fig.  49,  is  a  section  of 
granite  from  Cornwall,  with  crystals  of  orthoclase,  hexag- 
onal crystals  of  brown  mica,  and  colorless  quartz,  which 
a  higher  power  shows  to  contain  fluid  cavities,  magnified 
twenty-five  'diameters.  Plate  II,  Fig.  50,  a  volcanic  rock 
from  Peru,  composed  of  felspar,  dark  crystals  of  augite, 
hexagonal  crystals  of  dark  mica,  and  a  little  magnetic 
oxide  of  iron,  magnified  six  diameters.  Plate  II,  Fig. 
51,  lower  Silurian  roofing-slate,  cut  at  right  angles  to  the 
cleavage,  showing  that  the  latter  is  not  due  to  crystalline 
but  to  mechanical  arrangement,  magnified  two  hundred 
diameters.  Plate  II,  Fig.  52,  is  an  oolitic  specimen  from 
Peru,  regarded  as  an  eruptive  rock  by  D'Orbigny,  but 
shown  in  the  microscope  to  be  a  mere  aggregation  of 
sand,  etc.,  without  the  crystalline  character  of  eruptive 
rocks. 

Materials  of  Organic  Origin. — Rocks  and  strata  derived 
from  plants  or  animals  may  be  arranged  in  four  groups : 
1.  The  calcareous,  or  those  of  which  limestones  have  been 
formed,  as  corals,  corallines,  shells,  crinoids,  etc.  2.  The 
siliceous,  which  have  contributed  to  the  silica,  and  may 
have  originated  flints,  as  the  microscopic  shields  of  dia- 
toms and  siliceous  spiculae  of  sponges.  3.  The  phosphatic, 
as  bones,  excrement,  etc.  Fossil  excrements  are  called 
coprolites,  and  those  of  birds  in  large  accumulations, 
guano.  4.  The  carbonaceous,  or  those  which  have  afforded 
coal  and  resin,  as  plants. 

To  examine  the  structure  of  coal,  it  is  necessary  to  have 
very  thin  sections.  From  its  friability,  this  is  a  process 
of  great  difficulty.  The  Micrographic  Dictionary  recom- 


PI  ATE  II. 


Tig.    51x200 


52  x  30 


THE    MICROSCOPE    IN    MINERALOGY    AND   GEOLOGY.      93 

mends  the  maceration  of  the  coal  for  about  a  week  in  a 
solution  of  carbonate  of  potassium,  when  thin  slices  may 
be  cut  with  a  razor.  These  should  be  gently  heated  in 
nitric  acid,  and  when  they  turn  yellow,  washed  in  cold 
water  and  mounted  in  glycerin,  as  spirit  and  balsam  ren- 
der them  opaque.  Sometimes,  as  in  anthracite,  casts  of 
vegetable  fibres  may  be  obtained  in  the  ash  after  burning 
and  mounted  in  balsam. 

The  lignites  of  the  tertiary  period  show  a  vegetable 
structure  similar  to  the  woods  of  the  present  period,  but 
the  older  coal  of  the  palaeozoic  series  is  a  mass  of  decom- 
posed vegetable  matter  chiefly  derived  from  the  decay  of 
coniferous  wood,  analogous  to  the  araucarise,  as  is  seen 
from  the  peculiar  arrangement  of  the  glandular  dots  on 
the  woody  fibres.  Traces  of  ferns,  sigillarise,  calamites, 
etc.,  such  as  are  preserved  in  the  shales  and  sandstones  of 
the  coal  period,  are  also  met  with,  but  their  structure  has 
not  been  preserved. 

Professor  Heer,  of  Zurich,  has  described  and  classified 
several  hundred  species  of  fossil  plants  from  the  rniocene 
beds  of  Switzerland  by  the  outlines,  nervation,  and  micro- 
scopic structure  of  the  leaves  and  character  of  sections  of 
the  wood.  Several  hundred  kinds  of  insects  also  have 
been  found  in  the  same  strata.  It  is  remarkable  that  a 
great  part  of  this  fossil  flora  is  such  as  is  now  common 
to  America,  ^as  evergreen  oaks,  maples,  poplars,  ternate- 
leaved  pines,  and  the  representatives  of  the  gigantic 
sequoise  of  California. 

The  researches  of  palaeontologists  have  brought  to  light 
nearly  two  thousand  species  of  fossil  plants,  of  which 
about  one-half  belong  to  the  carboniferous  and  one-fourth 
to  the  tertiary  formations. 

The  rapid  multiplication  of  the  minute  microscopic 
organisms  called  diatoms,  is  such  that  Professor  Ehren- 
berg  affirms  it  to  have  an  important  influence  in  blocking 
up  harbors  and  diminishing  the  depth  of  channels.  These 


94  THE    MICROSCOPIST. 

organisms,  now  generally  regarded  as  plants,  are  exceed- 
ingly small,  and  are  usually  covered  by  loricse  or  shields 
of  pure  silica,  beautifully  marked,  as  if  engraved.  These 
loricse  or  shells  having  accumulated  in  great  quantities, 
have  given  rise  to  very  extensive  siliceous  strata.  Thus 
the  "infusorial  earth"  of  Virginia,  on  which  Richmond 
and  Petersburg  are  built,  is  such  a  deposit  eighteen  feet 
in  thickness.  The  polishing  material  called  Tripoli,  and 

FIG.  53. 


Fossil  Diatomacese,  etc.,  from  Mourne  Mountain,  Ireland:  a,  a,  a,  Gaillomlla  (Melo- 
seira)  procera,  and  G.  granulata;  d,  d,  d,  G.  biseriata  (side  view);  6,  6,  Surirella  plieata  ; 
c,  S,  craticula;  k,  S,  calodouica;  e,  Gomphonema  gracile;  /,  Cocconenia  fusidium;  g, 
Tabellaria  vulgaris;  h,  1'innularia  dactylus;  i,  P.  nobilis;  /,  Synedra  ulna.  (From 
Carpenter.) 

the  deposit  called  in  Sweden  and  Xorway  berg-mehl  or 
mountain  flour,  because  used  in  times  of  scarcity  to  mix 
with  flour  for  bread,  are  similarly  composed.  Strata  of 
white  rock  in  the  anthracite  region  of  Pennsylvania,  and 
from  the  sides  of  the  Sierra  Nevada  and  Cascade  ranges 
in  California  and  Oregon,  have  also  been  found  to  consist 
of  such  remains  (Fig.  53). 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.      95 

The  lowest  type  of  animal  life,  consisting  of  minute 
portions  of  sarcode  or  animal  jelly,  having  the  power  of 
putting  forth  prolongations  of  the  body  at  will,  contain 
some  forms  which  cover  themselves  with  shells,  usually 
many-chambered,  of  carbonate  of  lime.  From  the  pores 
in  these  shells,  through  which  the  root-like  processes  of 
sarcode  are  protruded,  they  are  called  Foraminifera. 

FIG.  54. 


Fossil  Polycystina,  etc.,  from  Barbadoes:  a,  Podocyrtis  mitra;  6,  Rhabdolithus  scep- 
trutn  ;  c,  Lychnocanium  falciferum;  d,  Encyrtidium  tubulus;  e,  Flustrella  concentrica; 
/,  Lychnocanium  lucerna;  g,  Encyrtidium  elegans;  h,  Dictyospyris  clathrus;  i,  Encyr- 
tidium mongolfieri;  A;,  Stephanolithis  spinescens;  /,  S,  nodosa;  m,  Lithocyclia  ocellus; 
n,  Cephalolithis  sylvina;  o,  Podocyrtis  cothurnata;  p,  Rhabdolithes  pipa.  (From  Car- 
penter.) 

Another  class,  the  Pofycystina,  secrete  a  siliceous  shell, 
usually  of  one  chamber.  The  accumulations  of  the  Fo- 
raminifera have  formed  our  chalk  beds,  while  the  Polycys- 
tina have  contributed  to  siliceous  strata,  like  the  Diato- 
macece  (Fig.  54). 

The  origin  of  white  chalk  strata  has  been  illustrated 


96  THE    MICROSCOPIST. 

by  the  deep-sea  soundings  made  preparatory  to  laying 
the  telegraph  cable  across  the  Atlantic  Ocean.  Professor 
Huxley  found  the  mud  composing  the  floor  of  the  ocean 
to  consist  of  minute  Rhizopods  or  Foraminifera,  of  the 
genus  Glohigerina,  together  with  Polycystina  and  Dia- 
toms, and  a  few  siliceous  spiculse  of  sponges.  These  were 
connected  by  a  mass  of  living  gelatinous  matter,  to  which 
he  has  given  the  name  of  Bathybius,  and  which  contains 
minute  bodies  termed  Coccoliths  and  Coccospheres,  which 
have  also  been  detected  in  fossil  chalk.  It  is  said  that 
95  percent,  of  the  mud  of  the  North  Atlantic  consists  of 
Globigerina  shells. 

To  examine  Foraminifera  in  chalk,  rub  a  quantity  to 
powder  in  water  with  a  soft  brush,  and  let  it  settle  for  a 
variable  time.  The  first  deposits  will  contain  the  larger 
specimens,  with  fragments  of  shell,  etc. ;  the  smaller  fall 
next,  while  the  amorphous  particles  suspended  in  the 
water  may  be  cast  aside.  After  drying  such  specimens 
as  may  be  selected  by  the  use  of  a  dissecting  microscope 
or  Coddington  lens,  etc.,  they  may  be  mounted  in  balsam. 

The  flint  found  in  chalk  often  contains  Xanthidia, 
which  are  the  sporangia  of  Desmidiacese,  as  well  as  speci- 
mens of  sponge,  Foraminiferal  shells,  etc.  They  must  be 
cut  as  other  hard  minerals. 

There  are  other  deposits  besides  chalk  which  are  seen 
by  the  microscope  to  consist  of  minute  shells,  corals, 
etc.  A  section  of  oolitic  stone  will  often  show  that  each 
rounded  concretion  is  composed  of  a  series  of  concentric 
spheres  inclosing  a  central  nucleus  which  may  be  a  forami- 
niferal  shell.  The  green  sand  formation  is  composed  of 
the  casts  of  the  interior  of  minute  shells  which  have  them- 
selves entirely  disappeared.  The  material  of  these  casts, 
chiefly  silex  colored  with  iron,  has  not  only  filled  the  cham- 
bers of  the  shells,  but  has  penetrated  the  canals  of  the 
intermediate  skeleton. 

The  more  recent  discovery  by  Drs.  Dawson  and  Carpen- 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.      97 

ter  of  the  organic  nature  of  those  serpentine  limestones 
in  the  Laurentian  formations  of  Canada  and  elsewhere, 
which  are  products  of  the  growth  of  the  gigantic  forami- 
niferal  Eozoon  Canadense,  over  immense  areas  ©f  the 
ancient  sea-bottom,  is  one  of  still  greater  interest  both  to 
the  student  of  Geology  and  of  Biology. 

This  immense  rhizopod  appears  to  have  grown  one  layer 
over  another,  and  to  have  formed  reefs  of  limestone  as  do 
the  living  coral-polyps.  Parts  of  the  original  skeleton, 
consisting  of  carbonate  of  lime,  are  still  preserved,  while 
certain  interspaces  have  been  filled  up  with  serpentine  and 
white  augite. 

Microscopic  Paleontology. — As  a  general  rule  it  is  only 
the  hard  parts  of  animal  bodies  that  have  been  preserved 
in  a  fossil  state. 

It  will  often  occur  that  the  inspection  of  a  microscopic- 
fragment  of  such  a  fossil  will  reveal  with  certainty  the- 
entire  nature  of  the  organism  to  which  it  belonged.  Thus 
minute  fossil  corals,  the  spines  of  Echinodermata,  the 
eyes  of  Trilobites,  etc.,  will  determine  the  position  to 
which  we  should  ascribe  the  specimen,  or  a  section  of  tooth 
or  bone  will  enable  the  rnicroscopist  to  assign  the  fossil  to 
its  proper  class,  order,  or  family.  Thus  Professor  Owen 
identified  by  its  fossil  tooth,  the  Labyrinthodon  of  War- 
wickshire, England,  with  the  remains  in  the  Wittemberg 
sandstones,  and  declared  it  to  be  a  gigantic  frog  with  some 
resemblances  both  to  a  fish,  and  a  crocodile.  This  predic- 
tion the  subsequent  discovery  of  the  skeleton  confirmed. 

The  minute  structure  of  teeth  differs  greatly  in  differ- 
ent animals.  In  the  shark  tribe  of  fishes  the  dentine  is 
very  similar  to  bone,  excepting  that  the  lacunae  of  bone 
are  absent.  In  man  and  in  the  Garni vora  the  enamel  is  a 
superficial  layer  of  generally  uniform  thickness,  while  in 
many  of  the  Herbivora  the  enamel  forms  with  the  cemen- 
tum  a  series  of  vertical  plates  which  dip  into  the  substance 
of  the  dentine.  Enamel  is  wanting  in  serpents,  Edentata, 


98  THE    MICROSCOPIST. 

and  Cetacea.  Such  differences  make  it  quite  possible  to 
distinguish  the  affinities  of  a  fossil  specimen  from  a  small 
fragment  of  tooth. 

In  a  similar  way  the  microscopic  characters  of  bone  vary. 
The  bones  of  reptiles  and  fishes  have  the  cancellated  struc- 
ture throughout  the  shaft,  while  the  lacunse  present  very 
great  varieties,  so  that  an  animal  tribe  may  be  determined 
by  their  measurement.  In  this  way  many  contributions 
have  already  been  made  to  palaeontology. 


CHAPTER   VIII. 

THE   MICROSCOPE   IN   CHEMISTRY. 

THE  value  of  microchemical  analysis,  and  the  simplicity 
of  its  processes,  commend  this  department  of  microscopy 
to  general  favor. 

A  large  proportion  of  the  actions  and  changes  produced 
by  reagents  may  be  observed  as  satisfactorily  in  drops  as 
in  larger  quantities.  The  decompositions  effected  by  a 
galvanic  battery  far  smaller  than  that  contained  in  a  lady's 
silver  thimble,  which  deflected  the  mirror  at  the  other  end 
of  the  Atlantic  Telegraph  Cable,  may  be  readily  observed 
with  a  microscope. 

Apparatus  and  Modes  of  Investigation.— A.  few  flat  and 
hollow  glass  slides,  thin  glass  covers,  test-tubes,  small 
watch-glasses,  a  spirit-Jamp  or  Bunsen's  burner,  constitute 
nearly  all  the  furniture  which  is  essential. 

Dr.  Wormley*  directs  that  a  drop  of  the  solution  to  be 
examined  should  be  placed  in  a  watch-glass,  and  a  small 
portion  of  reagent  added  with  a  pipette.  The  mixture 

*  The  Microchemistry  of  Poisons,  by  Dr.  Worraley. 


THE    MICROSCOPE    IN    CHEMISTRY.  99 

may  then  be  examined  with  the  microscope.  If  there  is 
no  precipitate,  let  it  stand  several  hours  and  examine  again. 
Dr.  Beale  prefers  a  flat  or  concave  slide,  and  suggests  that 
if  a  glass  rod  be  used  for  carrying  the  reagent,  it  must  be 
washed  each  time,  or  a  portion  may  be  transferred'  from 
the  slide  to  the  bottle.  He  also  advises  the  use  of  small 
bottles  with  capillary  orifices  for  reagents.  Dr.  Lawrence 
Smith  uses  small  pipettes  with  the  open  end  covered  by 
india-rubber. 

If  heat  be  required,  the  drop  may  be  boiled  on  the  slide 
over  a  spirit-lamp,  or  a  strip  of  platinum-foil  or  mica  may 
be  held  with  forceps  so  as  to  get  a  red  or  white  heat  from 
the  lamp  or  a  Bunsen  burner.  This  is  especially  needed 
to  get  rid  of  organic  matters. 

For  the  examination  of  earthy  materials,  as  carbonate 
or  phosphate  of  lime,  phosphate  of  ammonia  and  magne- 
sia, sulphates  or  chlorides,  a  small  fragment  may  be  placed 
on  a  slide  and  covered  with  thin  glass.  A  drop  of  nitric 
acid  is  then  put  near  the  edge  of  the  cover.  If  bubbles 
escape  a  carbonate  is  indicated.  Neutralize  the  acid  with 
ammonia ;  let  the  flocculent  precipitate  stand  awhile ; 
cover  and  examine  with  the  microscope.  After  a  time, 
amorphous  granules  and  prisms  will  show  phosphates  of 
ammonia,  magnesia,  and  lime.  Sulphates  are  shown  by 
adding  to  the  nitric  acid  solution  nitrate  of  barytes,  and 
chlorides  by  nitrate  of  silver. 

Dr.  Beale  recommends  adding  glycerin  to  the  test  solu- 
tions. The  reactions  are  slower  but  more  perfect,  and  the 
crystalline  forms  resulting  are  more  complete. 

If  a  sublimate  be  desired,  a  watch-glass  can  be  inverted 
over  another,  and  the  lower  one  containing  the  material, 
as  biniodide  of  mercury,  etc.,  heated  over  a  spirit-lamp, 
or  the  sublimation  may  be  made  in  a  reduction-tube. 

Preparation  of  Crystals  for  the  Polariscope. — Many  speci- 
mens may  be  prepared  by  concentrating  the  solution  with 
heat  and  allowing  it  to  cool.  It  should  not  be  evaporated 


100  THE    MICROSCOPIST. 

to  dryness.  Many  salts  may  be  preserved  in  balsam,  but 
some  are  injured  by  it,  and  need  glycerin  or  castor  oil  as 
a  preserving  fluid. 

The  method  of  crystallization  may  be  modified  in  vari- 
ous ways  so  as  to  obtain  special  results.  Thus  if  a  solu- 
tion of  sulphate  of  iron  is  suffered  to  dry  on  a  slide,  the 
crystals  will  be  arborescent  and  fern-like,  but  if  the  liquid 
is  stirred  with  a  glass  rod  or  needle  while  evaporating, 
separate  rhombic  prisms  will  form,  which  give  beautiful 
colors  in  the  polariscope.  Pyrogallic  acid  also  crystallizes 
in  long  needles,  but  ai  little  dust,  etc.,  as  a  nucleus,  brings 
about  a  change  of  arrangement  resembling  the  "eye"  of 
the  peacock's  tail. 

A  saturated  solution  dropped  into  alcohol,  if  the  salt  is 
insoluble  in  alcohol,  will  produce  instantaneous  crystals. 

To  obtain  the  best  results,  some  crystals,  as  salicin, 
should  be  fused  on  a  slide  over  the  lamp,  and  the  matter 
spread  evenly  over  the  surface.  This  may  be  done  with 
a  hot  needle.  The  temperature  greatly  affects  the  char- 
acter of  the  crystallization.  If  very  hot,  the  crystals  run 
in  lines  from  a  common  centre.  A  medium  temperature 
produces  concentric  waves. 

Many  new  forms  result  from  uniting  different  salts  in 
different  proportions.  The  knowledge  of  these  different 
effects  can  only  be  attained  by  experience. 

Sections  of  crystals,  as  nitrate  of  potash,  etc.,  to  show 
the  rings  and  cross  in  the  polariscope,  are  difficult  to 
make.  After  cutting  a  plate  with  a  knife  to  about  one- 
fourth  of  an  inch  thick,  it  may  be  filed  with  a  wet  file  to 
one-sixth  of  an  inch,  smoothed  on  wet  glass  with  fine 
emery,  and  polished  on  silk  strained  over  a  piece  of  glass, 
and  rubbed  with  a  mixture  of  rouge  and  tallow.  The 
nitre  must  be  rubbed  till  quite  dry,  and  the  vapor  of  the 
fingers  prevented  by  the  use  of  gloves. 

For  a  general  account  of  the  use  of  polarized  light,  see 
Chapter  YI. 


THE    MICROSCOPE    IN    CHEMISTRY.  101 

The  Use  of  the  Microspectroscope. — We  have  already  de- 
scribed this  accessory  in  Chapter  III.  It  promises  im- 
portant results  in  chemical  analysis,  but  requires  delicate 
observation  and  exact  measurements,  together  with  a 
careful  and  systematic  study  of  a  large  number  of  colored 
substances. 

In  using  the  microspectroscope,  much  depends  on  the 
regulation  of  the  slit.  It  should  be  just  wide  enough  to 
give  a  clear  spectrum  without  irregular  shading.  As  a 
general  rule,  it  should  be  just  wide  enough  to  show  Frau- 
enhofer's  lines  indistinctly  in  daylight.  The  slit  in  the 
side  stage  should  be  such  that  the  two  spectra  are  of 
equal  brilliancy.  No  light  should  pass  up  the  microscope 
but  such  as  has  passed  through  the  object  under  exam- 
ination. This  sometimes  requires  a  cap  over  the  object- 
glass,  perforated  with  an  opening  of  about  one-sixteenth 
of  an  inch  for  a  one  arid  a  half  inch  objective. 

The  number,  position,  width,  and  intensity  of  the  ab- 
sorption-bands are  the  data  on  which  to  form  an  opinion 
as  to  the  nature  of  the  object  observed,  and  Mr.  Sorby 
has  invented  a  set  of  symbols  for  recording  such  observa- 
tions. (See  Dr.  Beale's  How  to  Work  with  the  Microscope.} 
These  bands,  however,  do  not  relate  so  much  to  the  ele- 
mentary constitution  as  to  the  physical  condition  of  the 
substance,  and  vary  according  to  the  nature  of  the  solvent, 
etc.,  yet  many  structures  give  such  positive  effects  as  to 
enable  us  to  decide  with  confidence  what  they  are. 

Colored  beads  obtained  by  ordinary  blowpipe  testing, 
sections  of  crystals,  etc.,  cut  wedge-shaped  so  as  to  vary 
their  thickness,  often  give  satisfactory  results.  But 
minute  quantities  of  animal  and  vegetable  substances,  as 
blood-stains,  etc.,  dissolved  and  placed  in  short  tubes 
fastened  endwise  on  glass  slides,  or  in  some  other  conve- 
nient apparatus,  offer  the  most  valuable  objects  of  re- 
search. 

To  measure  the  exact  position  of  the  absorption-bands, 


102 


THE    MICROSCOPIST. 


the  micrometer  already  described  may  be  used,  or  Mr. 
Sorby's  apparatus,  giving  an  interference  spectrum  with 
twelve  divisions,  made  by  two  Mcol's  prisms,  with  an 
intervening  plate  of  quartz  of  the  required  thickness. 

The  value  of  this  mode  of  investigation  in  medical 
chemistry,  and  for  purposes  of  diagnosis  or  jurisprudence, 
may  be  seen  by  the  following  illustrations:* 

Pettenkofer's  Test  for  Bile  (Fig.  55).— To  a  few  drops  of 
bile  in  a  porcelain  dish,  add  a  drop  of  solution  of  cane- 


A    a   P  C 


H  TT 


Pettenkofer's  Bile-Test. 


sugar,  and  then  concentrated  sulphuric  acid  drop  by  drop, 
with  agitation.  The  mixture  becomes  a  purple-red  color, 
and  shows  a  spectrum  as  in  the  figure.  The  color  will 
be  destroyed  by  water  and  alcohol. 

Tests  for  Blood. — Haematocrystalline,  or  cruorin,  com- 
posed of  an  albuminoid  substance  and  hsematin,  generally 
crystallizes  in  tetrahedra  or  octahedra.  In  blood  from 


A    a   B  C 


H  IT 


Blood. 


the  horse  and  from  man  only  an  amorphous  deposit  is 
found.  The  watery  solution  of  this  substance  properly 
diluted,  shows  two  remarkable  bands  of  absorption,  and 
obscuration  of  the  blue  and  violet  end  of  the  spectrum 
(Fig.  56).  As  the  blood  of  all  vertebrates  shows  the  same 

*  See  Thudichum's  Manual  of  Chemical  Physiology.    New  York,  1872. 


THE    MICROSCOPE    IN    CHEMISTRY. 


103 


bands,  it  is  judged  that  hamate-crystalline  is  present  in  it 
as  such,  and  not  formed  from  it.  By  treating  a  solution 
of  blood  which  exhibits  the  two  absorption-bands  with 
hydrogen,  or  with  a  solution  of  ferrous  sulphate  contain- 
ing tartaric  acid  and  excess  of  ammonia,  taking  care  to 


A    a   E  C 


H  H1 


Reduced  Haeiuatoerystalline. 


exclude  the  air,  the  color  of  the  solution  changes  to  pur- 
ple, and  the  spectroscope  shows  only  one  broad  band  in- 
stead of  two  (Fig  57).  Shaking  with  air  will  restore  the 
two  bands.  By  treating  blood  with  hydrothion  or  am- 


FIG.  58. 


A    a   B  C 


E  1) 


H  FT 


TI 

1 

51 

_. 


Blood  treated  with.  Amni 


monium  sulphide,  three  bands  make  their  appearance,  as 
in  Fig.  58. 

Hsematin  is  seen  by  the  microscope  to  consist  of  small 


A      n     7?   fl 


Four-banded  Hsematin. 


rhombic  crystals.  Dissolved  in  alcohol  and  a  little  sul- 
phuric acid,  the  spectrum  shows  four,  and  under  some 
circumstances  five,  bands  (Fig.  59).  Rendered  alkaline 


104 


THE    MICROSCOPIST. 


by   caustic   potash,  one   broad  band   appears  (Fig.  60\ 
Acid  will  restore  the  former  spectrum. 

Dissolve  haernatin  in  water  with  a  little  caustic  potash. 


A    a    7? 


JT    77' 


iilii 


Alkaline  liaeuialin. 


To  a  solution  of  ferrous  sulphate,  add  tartaric  acid  and 
then  ammonia  till  alkaline.  Pour  a  little  of  the  clear 
mixture  into  the  hsematin  solution.  The  spectrum  of  re- 


A    a   B  C 


Reduced  Haematin. 


duced  hsematin  will  show  two  bands  (Fig.  61).     Shaking 
with  air  will  restore  the  former  spectrum. 

Liutein  Spectra. — The  juice  of  the  corpora  lutea,  to  which 
sulphuric  acid  and  a  little  sugar  is  added,  gives  a  fine 


A    a    E  C 


Juice  of  Corpora  Lutea  with  Sulphuric  Acid. 

purple  color,  and  shows  in  the  spectroscope  one  band  in 
the  green  (Fig.  62).  Its  chloroform  solution,  examined 
with  lime-light,  shows  two  bands  in  blue  (Fig.  63).  An 
alcoholic  or  ethereal  solution  gives  a  third  one  in  the 
violet. 


THE    MICROSCOPE    IN    CHEMISTRY. 


105 


Cysto  lutein,  or  the  yellow  fluid  of  an  ovarian  cyst, 
shows  with  the  lime-lio;ht  three  bands  in  blue,  in  the 


A    a    Ji 


H  IT 


Chloroform  Solution  of  Corpora  Lutea. 


same  position  as  the  chloroform  solution  of  lutein  (Fig. 
64). 

The  serum  of  blood,  etc.,  shows  the  bands  of  hsemato- 


A    a    B  C 


Cysto-Luteiu  from  au  Ovarian  Cyst. 

crystalline  and  one  or  two  doubtful  bands,  as  in  the  figure 
(Fig.  65). 

Dr.  Richardson,  of  Philadelphia,  gives  the  following 
directions  for  examining  blood-stains:  Procure  a  glass 
slide  with  a  circular  excavation,  and  moisten  the  edges 
of  the  cavity  with  a  small  drop  of  diluted  glycerin.  Lay 


A    a   B  C 


Sero-Lutein. 


a  clean  glass  cover,  a  little  larger  than  the  excavation,  on 
white  paper,  .and  put  on  it  the  smallest  visible  fragment 
of  blood-clot.  "With  a  needle,  put  on  the  centre  of  the 
cover  a  speck  of  glycerin,  not  larger  than  a  full  stop  (.), 


106  THE    MICROSCOPIST. 

and  with  a  dry  needle  push  the  blood  to  the  edge  that  it 
may  he  just  moistened  with  the  glycerin.  Place  the  slide 
on  the  cover  so  that  the  glycerin  edges  of  the  cavity  may 
adhere,  and  turning  it  over,  transfer  it  to  the  stage  of  the 
microscope.  Thus  a  minute  quantity  of  a  strong  solution 
of  hsemoglobulin  is  obtained,  the  point  of  greatest  density 
of  which  may  be  found  by  a  one-fourth  objective,  and 
tested  by  the  spectroscopic  eye-piece  and  with  high  powers. 
The  tiny  drop  may  be  afterwards  wiped  off  with  moist 
blotting-paper,  and  a  little  fresh  tincture  of  guaiacum 
added,  showing  the  blue  color  of  the  guaiacum  blood-test. 
Inverted  Microscope  of  Dr.  Lawrence  Smith. — In  ordinary 
chemical  investigations  there  is  some  risk  of  injuring  the 
polish  of  the  lenses,  as  well  as  the  brass  work  of  the  mi- 
croscope, without  very  great  care.  This  is  particularly 
the  case  in  observing  the  effects  of  heat  or  of  strong  acids. 
To  obviate  this  difficulty,  Dr.  Lawrence  Smith  contrived 
a  plan  for  an  inverted  microscope,  which  has  been  con- 
structed by  Nachet  of  Paris.  The  optical  part  of  the  in- 
strument is  below  the  stage,  and  is  furnished  with  a  pecu- 
liar prism,  by  which  the  rays  from  the  objective  are  bent 
into  a  conveniently  inclined  body.  The  illuminating  ap- 
paratus is  above  the  stage.  This  construction  renders  the 
instrument  well  adapted  to  chemical  investigations. 

GENERAL  MICROCHEMICAL  TESTS. 

Dr.  Wormley  has  directed  attention  to  some  necessary 
cautions.  He  shows  that  many  substances  which  may 
readily  be  detected  in  a  pure  state,  even  in  very  minute 
quantities  by  the  microscope,  are  difficult  to  detect  when 
mixed  with  complex  organic  materials.  This  is  especially 
applicable  to  the  alkaloids,  which  should  be  separated 
from  such  mixtures  by  the  use  of  the  dialyzer — a  hoop 
with  a  bottom  of  parchment-paper,  etc. — or  extracted 
with  ether  or  chloroform. 


THE    MICROSCOPE    IN    CHEMISTRY.  107 

The  purity  of  all  reagents  should  be  carefully  estab- 
lished, and  they  should  be  kept  in  hard  German  glass 
bottles,  and  only  distilled  water  used  in  all  our  researches. 

The  true  nature  of  a  reaction  that  is  common  to  several 
substances  may  often  be  determined  with  the  microscope. 
Thus  a  solution  of  nitrate  of  silver  becomes  covered  with 
a  white  film  when  exposed  to  several  different  vapors,  but 
hydrocyanic  acid  is  the  only  one  which  is  crystalline. 
This  will  detect  100,000th  of  a  grain  of  the  acid.  A  slip 
of  clean  copper  boiled  in  a  hydrochloric  acid  solution  of 
arsenic,  mercury,  antimony,  etc.,  becomes  coated  with  the 
metal,  but  when  heated  in  a  reduction-tube,  arsenic  only 
yields  a  sublimate  of  octahedral  crystals,  and  mercury 
only  will  furnish  metallic  globules. 

A  solution  of  iodine  produces  distinct  reaction  with 
100,000th  of  a  grain  of  strychnine  in  solution  in  1  grain 
of  water,  but  as  this  is  common  to  other  alkaloids,  other 
tests  are  needed.  Yet  the  absence  of  such  a  reaction 
shows  the  absence  of  the  alkaloid. 

The  degree  of  dilution  is  important.  Thus  bromine  with 
atropin  yields  a  crystalline  deposit  from  1  grain  of  a 
20,000th  or  stronger  dilution,  but  not  with  diluter  solu- 
tions. A  limited  quantity  of  sulphuretted  hydrogen 
throws  down  from  corrosive  sublimate  a  white  deposit, 
while  excess  produces  a  black  precipitate. 

Blue  and  Reddened  Litmus  Paper  are  used  as  tests  for 
acids  and  alkalies.  It  is  a  bibulous  paper  dyed  in  infu- 
sion of  litmus.  The  red  is  made  by  adding  a  little  acetic 
acid  to  the  infusion.  Dry  substances  and  vapors  require 
the  paper  to  be  moistened  with  distilled  water.  If  the 
acid  reaction  depends  on  carbonic  acid,  warming  the  paper 
on  a  slide  over  a  lamp  will  restore  the  color.  So  if  a 
volatile  alkali,  ammonia  or  carbonate  of  ammonia,  have 
made  the  red  paper  blue,  its  color  will  be  restored  by  a 
gentle  heat.  Sometimes  the  infusion  of  litmus  is  more 
convenient  than  the  paper. 


108  THE    MICROSCOPIST. 

Alcohol  coagulates  albuminous  matter. 

Ether  dissolves  fat. 

Acetic  Acid  will  dissolve  phosphate  or  carbonate  of  lime, 
but  not  the  oxalate. 

Nitrate  of  Barytes  in  cold  saturated  solution  is  a  test  for 
sulphuric  and  phosphoric  acids.  The  precipitated  sulphate 
of  baryta  is  insoluble  in  acids  and  alkalies.  The  phosphate 
is  soluble  in  acids  arid  insoluble  in  ammonia. 

Nitrate  of  Silver. — A  solution  of  60  grains  to  the  ounce 
of  water  is  a  convenient  test  for  chlorides  and  phosphates. 
Chloride  of  silver  is  white,  soluble  in  ammonia  and  insolu- 
ble in  nitric  acid.  The  tribasic  phosphate  of  silver  is  yel- 
low, and  soluble  in  excess  of  ammonia  or  of  nitric  acid. 

Oxalate  of  Ammonia  is  a  test  for  salts  of  lime.  Dissolve 
the  material  in  nitric  acid,  and  add  excess  of  ammonia. 
Dissolve  the  flocculeut  precipitate  in  excess  of  acetic  acid, 
and  add  the  oxalate  of  ammonia.  Oxalate  of  lime  is  in- 
soluble in  alkalies  and  acetic  acid,  but  soluble  in  strong 
mineral  acids. 

Iodine  is  a  test  for  starch,  coloring  it  blue.  Albuminous 
tissues  are  colored  yellow,  and  vegetable  cellulose  a  brown- 
ish-yellow. The  addition  of  sulphuric  acid  turns  cellulose 
blue. 

DETERMINATION  OF  SUBSTANCES. 
ALKALIES. 

Bichloride  of  platinum  precipitates  from  salts  of  potash 
or  ammonia  a  yellow  double  chloride,  which  crystallizes 
in  beautiful  octahedra.  It  has  no  precipitating  effect  on 
solutions  of  soda.  Polarized  light  will  distinguish  the 
800,000th  of  a  grain  of  double  chloride  of  sodium  and 
platinum  by  its  beautiful  colors  from  the  chloride  of 
potassium  and  platinum,  or  of  platinum  alone.  The 
double  chloride  of  platinum  and  potassium  may  be  dis- 
tinguished from  that  of  ammonia  by  heating  to  redness, 
treating  with  hot  water,  and  acting  on  with  nitrate  of 


THE    MICROSCOPE    IN    CHEMISTRY.  109 

silver.  The  ammonium  compound  after  ignition  leaves 
only  the  platinum,  which  gives  no  precipitate  with  nitrate 
of  silver,  while  the  potassium  chloride  yields  a  white  pre- 
cipitate of  chloride  of  silver. 

Antimoniate  of  potash  throws  down  from  solutions  of 
soda  and  its  neutral  salts  a  white  crystalline  antimoniate 
of  soda,  the  forms  of  which  vary  according  to  the  strength 
of  the  solution  ;  generally  they  are  rectangular  plates  and 
octahedra. 

ACIDS. 

Sulphuric. — In  solutions  acidulated  with  hydrochloric 
or  nitric  acid,  the  chloride  or  nitrate  of  baryta  produces 
a  white  precipitate.  Yeratrin  added  to  a  drop  of  concen- 
trated sulphuric  acid  produces  a  crimson  solution,  or  de- 
posit if  evaporated. 

Nitric. — Heated  with  excess  of  hydrochloric  acid  elimi- 
nates chlorine,  which  will  dissolve  gold  leaf.  A  blood- 
red  color  is  produced  when  nitric  acid  or  a  nitrate  is  mixed 
with  a  sulphuric  acid  solution  of  brucin. 

Hydrochloric. — Nitrate  of  silver  precipitates  amorphous 
chloride  of  silver;  soluble  in  ammonia,  but  insoluble  in 
nitric  and  sulphuric  acid. 

Oxalic. — Nitrate  of  silver  precipitates  amorphous  oxa- 
late  of  silver ;  soluble  in  nitric  acid  and  also  in  solution 
of  ammonia. 

Hydrocyanic. — Put  a  drop  of  acid  solution  .in  a  watch- 
glass,  invert  another  over  it  containing  a  drop  of  solution 
of  nitrate  of  silver,  and  a  crystalline  film  will  form.  A 
solution  of  hydrocyanic  acid  treated  with  caustic  potash 
or  soda  and  then  with  persulphate  of  iron  yields  Prussian 
blue. 

Phosphoric. — A  mixture  of  sulphate  of  magnesia,  chlo- 
ride of  ammonium,  and  free  ammonia  produces  in  solu- 
tions of  free  phosphoric  acid  and  alkaline  phosphates 
white  feathery  or  stellate  crystalline  precipitate  of  ammo- 


110  THE    MICROSCOPIST. 

nio-phosphate  of  magnesia.   A  slower  crystallization  gives 
prisms. 

METALLIC    OXIDES. 

These  may  usually  be  determined  by  treating  a  small 
portion  of  solution,  acidulated  with  hydrochloric  acid,  by 
sulphuretted  Irydrogen ;  another,  and  neutral  portion  with 
sulphuret  of  ammonium ;  and  a  third  with  carbonate  of 
soda. 

Antim.ony. — Sulphuretted  hydrogen  throws  down  or- 
ange-red precipitate  from  tartar-emetic  solutions,  etc. 

Arsenic  yields  white  octahedral  crystals  of  arsenious 
acid  when  sublimed.  Arsenious  acid  may  be  reduced  to 
metallic  arsenic  by  heating  to  redness  in  a  tube  with 
charcoal  and  carbonate  of  soda.  A  solution  of  arsenious 
acid  yields  octahedral  crystals  by  evaporation,  so  as  to 
determine  with  the  microscope  1000th  to  10,000th  of  a 
grain. 

Ammonio-nitrate  of  silver  throws  down  from  an  aque- 
ous solution  of  arsenious  acid  a  bright  yellow  precipitate, 
arnmonio-sulphate  of  copper  a  green  precipitate,  and  sul- 
phuretted hydrogen  a  bright  yellow. 

Mercury. — Bichloride  of  mercury,  moistened  with  a  drop 
of  solution  of  iodide  of  potassium,  assumes  the  bright 
scarlet  color  of  biniodide  of  mercury.  A  strong  solution 
of  caustic  potash  or  soda  turns  bichloride  of  mercury  yel- 
low from  the  formation  of  protoxide ;  but  calomel  or  chlo- 
ride of  mercury  is  blackened  from  formation  of  suboxide. 
Heated  in  a  reduction-tube  with  dry  carbonate  of  soda, 
the  sublimate  shows  under  the  microscope  small,  opaque, 
spherical  globules  of  mercury.  Dr.  Wormley  states  that 
a  globule  of  mercury  or  "artificial  star"  may  be  discrim- 
inated by  the  one-eighth  objective  if  it  be  but  the 
25,000th  of  an  inch  in  diameter,  weighing  about  the 
9,000,000,000th  of  a  grain;  globules  of  ^^th  of  an  inch 
diameter  weigh  about  70,000,000th  of  a  grain. 


THE    MICROSCOPE    IN    CHEMISTRY.  Ill 

Lead. — Sulphuretted  hydrogen  gives  a  hlack  amor- 
phous deposit.  Sulphuric  and  hydrochloric  acids  yield  a 
white  precipitate.  Chloride  of  lead  crystallizes  in  needles. 
Iodide  of  potassium  gives  a  bright  yellow  precipitate,  sol- 
uble in  boiling  wrater,  and  crystallizing  in  six-sided  plates. 
Bichromate  of  potassium  yields  a  bright  yellow  amor- 
phous deposit. 

Copper. — Sulphuretted  hydrogen  gives  a  brown  or  black- 
ish deposit ;  ammonia  a  blue  or  greenish-blue  amorphous 
precipitate,  or  in  dilute  solutions  a  blue  color  to  the  liquid  ; 
caustic  alkali,  a  similar  precipitate,  which  on  boiling  in 
excess  of  reagent  becomes  black,  bttt  if  grape-sugar,  or 
some  other  organic  agents,  be  present,  a  yellow  or  red 
precipitate  of  suboxide  of  copper  occurs.  Arsenite  of 
potassium  produces  a  bright  green. 

Zinc. — Sulphuretted  hydrogen  gives  a  white  amorphous 
deposit — the  only  white  sulphuret.  Alkalies  produce  a 
white  hydrated  oxide  of  zinc. 

ALKALOIDS. 

The  editors  of  the  Micrographic  Dictionary  refer  to  a  paper 
of  Dr.  T.  Anderson,  in  the  Edinburgh  Monthly  Journal, 
where  he  shows  that  the  microscope  readily  distinguishes 
the  more  common  alkaloids  from  each  other  by  the  form 
of  their  crystals  and  of  their  sulphocyanides.  The  alka- 
loids are  first  dissolved  in  dilute  hydrochloric  acid,  then 
precipitated  on  a  glass  plate  with  a  solution  of  ammonia, 
or  if  the  sulphocyanide  is  required,  with  a  strong  solution 
of  sulphocyanide  of  potassium.  It  may  then  be  placed 
under  the  microscope.  The  solution  should  not  be  too  con- 
centrated. This  branch  of  investigation  has  been  greatly 
promoted  by  the  elegant  work  of  Dr.  Wormley,  already 
referred  to,  on  the  Microchemistry  of  Poisons. 

Atropin. — Ammonia  throws  down  an  amorphous  pre- 
cipitate. One  grain  of  a  T^th  grain  solution  yields  to 


112  THE    MICROSCOPIST. 

caustic  potash  or  soda  a  precipitate  which,  when  stirred 
with  a  glass  rod,  becomes  a  mass  of  crystals,  as  in  Plate 
til,  Fig.  66.  The  Sulphocyanide  of  potassium  gives  no 
precipitate. 

Aconitin. — No  characteristic  test,  except  the  physiologi- 
cal one;  yo^th  of  a  grain  produces  on  the  end  of  the 
tongue  a  peculiar  tingling  and  numbness,  lasting  for  an 
hour;  TJotn  grain  in  alcohol,  rubbed  on  the  skin,  pro- 
duces temporary  loss  of  feeling. 

Brucin  or  Bruda. — Potash  or  ammonia  produces  stellar 
crystals.  Sulphocyanide  of  potassium,  feathery,  or  sheaf- 
like.  (Plate  III,  Fig.  67.)  Nitric  acid  produces  a  blood- 
red  color,  changing  to  yellow  by  heat.  On  cooling  the 
latter  and  adding  protochloride  of  tin,  it  becomes  a  beau- 
tiful purple.  Ferricyanide  of  potassium,  with  T  ^  Oth  grain 
of  brucin  yields  the  most  brilliant  polariscope  crystals. 
(Plate  III,  Fig.  68). 

Cmchonine. — Ammonia  produces  granular  radiating 
crystals.  (Plate  III,  Fig.  69.)  Sulphocyanide  of  potas- 
sium six-sided  plates,  some  irregular.  (Plate  III,  Fig.  70.) 

Conine. — This  alkaloid  and  nicotin  are  distinguished 
from  other  alkaloids  by  being  liquid  at  ordinary  tempera- 
tures, and  by  their  peculiar  odor.  Conine  may  be  known 
from  nicotin  by  its  odor  and  sparing  solubility  in  water, 
by  yielding  crystalline  needles  to  the  vapor  or  solution  of 
hydrochloric  acid,  a  white  precipitate  with  corrosive  sub- 
limate, and  a  dark-brown  precipitate  with  nitrate  of  silver. 

Codein. — Ammonia  or  alkalies  give  a  white  amorphous 
deposit.  Sulphocyanide  of  potassium,  crystalline  needles. 
A  solution  of  iodine  in  iodide  of  potassium,  a  reddish- 
brow^  precipitate,  which  becomes  crystalline.  This  is 
soluble  in  alcohol,  from  which  it  separates  in  plates  (Plate 
III,  Fig.  71),  which  appear  beautiful  in  the  polariscope. 

Daturin. — According  to  Dr.  Wormley,  this  is  identical 
with  atropin. 

Narcotin. — In  its  pure   state   crystallizes    in  rhombic 


PLATE  III. 


FIG.  66. 


FIG.  67. 


*        * 


FI0.71. 


^ 
\> 


FIG.  72. 


** 


FIG.  73. 


FIG.  74. 


FIG.  70. 


o  ,    O 


O 


FIG.  75. 


THE    MICROSCOPE    IN    CHEMISTRY.  113 

prisms,  or  oblong  plates.  Ammonia,  the  alkalies,  and  their 
carbonates  produce  tufts  of  crystals  (Plate  III,  Fig.  7^). 
A  drop  of  aqueous  solution  of  a  salt  of  narcotin,  exposed 
to  vapor  of  ammonia,  is  covered  with  a  crystalline  film  if 
it  only  contains  g^^th  of  its  weight  of  alkaloid. 

Morphine. — When  pure  crystallizes  in  short  rectangular 
prisms.  Sulphuric  acid  dissolves  them,  and  if  bichromate 
of  potash  be  added,  green  oxide  of  chromium  results.  Con- 
centrated nitric  acid  turns  it  orange-red,  and  dissolves  it. 
A  strong  solution  treated  with  a  strong  solution  of  nitrate 
of  silver  and  gently  heated,  decomposes  the  latter  and  pro- 
duces a  shining  crystalline  precipitate  of  metallic  silver, 
In  dilute  solutions,  alkalies  precipitate  a  crystalline  form 
(Plate  III,  Fig.  73).  No  precipitate  with  sulphocyanide- 
of  potassium  unless  highly  concentrated. 

Quinine. — Amorphous  precipitate  with  ammonia.  Su'l- 
phocyanide  of  potassium  gives  irregular  groups  of  acicu^ 
lar  crystals,  like  those  produced  by  strychnine,  but  longer 
and  more  irregular  (Plate  III,  Fig  74\  The  solution 
should  be  dilute,  and  twenty-four  hours  allowed  for  the 
crystals  to  form. 

The  iodo-disulphate,  or  Ilerapathite,  gives  crystals  of  a 
pale  olive-green  color,  which  possess  a  more  intense  polar- 
izing power  than  any  other  known  substance.  Dr.  Hera- 
path  proposed  this  as  a  delicate  test  for  quinine.  A  drop 
of  test-liquid — made  with  3  drachms  of  acetic  acid,  1 
drachm  of  rectified  spirits,  and  6  drops  of  dilute  sulphuric 
acid — is  placed  on  a  slide  and  the  alkaloid  added.  When 
dissolved  a  little  tincture  of  iodine  is  added,  and  after  a 
time  the  salt  separates  in  little  rosettes.  By  careful  manip- 
ulation crystals  of  this  salt  may  be  formed  large  enough 
to  replace  Nicol's  prisms  or  tourmaline  plates  in  the  polar- 
izing apparatus.  When  the  crystals  of  Ilerapathite  cross 
each  other  at  a  right-angle,  complete  blackness  results. 
Intermediate  positions  give  a  beautiful  play  of  colors. 

Strychnine. — Ammonia  gives  small  prismatic  crystals, 

8 


114  THE    MICROSCOPIST. 

some  crossed  at  60°  (Plate  III,  Fig.  75).  Sulphocyanide 
of  potassium  produces  flat  needles,  often  in  groups.  Iodine 
in  iodide  of  potassium  gives  a  reddish-brown  amorphous 
precipitate,  crystalline  in  dilute  solutions.  When  pure, 
strychnine  appears  in  colorless  octahedra,  lengthened 
prisms  or  granules.  To  a  solution  of  the  alkaloid  or  its 
salts  in  a  drop  of  pure  sulphuric  acid,  which  produces  no 
-color,  add  a  small  crystal  of  bichromate  of  potash,  and 
•stir  slowly  with  a  pointed  glass  rod.  A  blue  color  will 
appear,  passing  into  purple,  violet,  and  red.  The  bright 
yellow  crystals  of  chromate  of  strychnia,  if  dried  and 
touched  with  sulphuric  acid,  will  also  show  the  color  test. 
This  is  said  to  be  delicate  enough  to  show  Y^n'ooTj^  °*'  a 
grain  of  strychnine.  The  tetanic  convulsions  of  frogs  im- 
mersed in  a  solution  of  strychnine,  or  after  injections  of 
the  solution  in  lungs  or  stomach,  etc  ,  is  also  a  very  deli- 
cate test. 

Veratrin  and  its  salts  treated  in  the  dry  state  with  con- 
centrated sulphuric  acid,  slowly  dissolve  to  a  reddish-yel- 
low, or  pink  solution,  which  becomes  crimson-red.  The 
process  is  accelerated  by  heat. 

Narcein,  touched  with  the  cold  acid,  becomes  brown, 
brownish-yellow,  and  greenish-yellow,  and  if  heated,  a 
dark  purple-red. 

Solanin  turns  orange-brown,  and  later  purplish-brown. 

Piperin  turns  orange-red  to  brown. 

Salicin  gives  to  the  acid  a  crimson  pink,  changing  to 
black. 

Papaverin  gives  a  fading  purple. 

CRYSTALLINE   FORMS   OF    VARIOUS   SALTS. 

Our  limits  forbid  extended  description,  yet  a  few  forms 
of  frequent  recurrence  will  be  useful  to  the  student.  For 
crystals  in  plants  or  from  animal  secretions  reference  may 
be  made  also  to  succeeding  chapters. 

Salts  of  Lime. — The  carbonate  sometimes  occurs  in  ani- 


PLATE  IV. 


FIG.  76. 


I 


FIG.  80. 

\ 


FIG.  77. 


FIG.  81. 


8* 


FIG.  78. 


' 


FIG.  82. 


FIG.  79. 


FIG.  83. 


FIG.  84. 


THE    MICROSCOPE    IN    CHEMISTRY.  115 

mal  secretions  in  the  form  of  little  spheres  or  disks,  con- 
sisting of  groups  of  radiating  needles.  In  otoliths  it  is 
often  in  minute  hexagonal  prisms  with  trilateral  summits. 
It  is  deposited  from  water  in  irregular  forms,  all  of  which 
are  grouped  needles.  Sometimes  it  assumes  the  rhombo- 
hedral  form,  as  in  the  oyster  shell  (Plate  IV,  Fig.  76). 
In  any  doubtful  case,  test  as  described  at  pages  99  and 
108. 

Lactate  of  Lime  gives  microscopic  crystals,  consisting  of 
delicate  radiating  needles  (Plate  IV,  Fig.  77). 

Oxalate  of  Lime  occurs  as  square  flattened  octahedra,as 
square  prisms  with  quadrilateral  pyramids,  as  fine  needles, 
and  as  ellipsoidal  flattened  forms,  sometimes  constricted 
so  as  to  resemble  dumb-bells  (Plate  IV,  Fig.  78). 

Phosphate  of  Lime  is  usually  in  the  form  of  thin  rhombic 
plates  (Plate  IV,  Fig.  79). 

Sulphate  of  Lime  rapidly  formed,  as  in  chemical  testing, 
gives  minute  needles  or  prisms  (Plate  IV,  Fig.  80).  When, 
more  slowly  formed,  these  are  larger  and  mixed  with 
rhombic  plates. 

Soda  Salts. — Chloride  of  Sodium  or  common  salt  gener- 
ally forms  a  cube,  terminated  by  quadrangular  pyramids 
or  depressions  (Plate  IV,  Fig.  81).  The  crystals  do  not 
polarize  light. 

Plate  IV,  Fig.  82,  represents  crystals  of  oxalate  of  soda, 
and  Plate  IV,  Fig.  83,  those  of  nitrate. 

Magnesia  Salts. — Ammonio-phosphate,  or  triple  phosphate, 
is  often  found  in  animal  secretions.  The  most  common 
form  is  prismatic,  but  sometimes  it  is  feathery  or  stellate 
(Plate  IV,  Fig.  84). 

Sulphate  of  Magnesia  forms  an  interesting  polarizing 
object. 

A  most  instructive  series  of  salts  may  be  made  by 
rapidly  crystallizing  some  on  glass  slides,  and  allowing 
others  to  deposit  more  slowly.  In  this  way  a  set  of  speci- 
mens may  be  prepared  for  comparison. 


116  THE    MICROSCOPIST. 

CHAPTER   IX. 

THE  MICROSCOPE  IN  BIOLOGY. 

THE  science  of  biology  (from  /9<«c,  life),  which  treats  of 
the  forms  and  functions  of  living  beings,  would  be  crude 
and  imperfect  without  the  aid  of  the  microscope.  What- 
ever might  be  learned  by  general  observation,  we  should 
miss  the  fundamental  laws  of  structure  and  the  unity 
•which  we  now  know  pervades  distant  and  ap'parently 
different  organs,  as  well  as  distinct  species,  if  we  were 
deprived  of  the  education  which  microscopy  gives  the 
eye  and  hand. 

The  evident  differences  between  living  and  non-living 
bodies  led  to  ancient  theories  of  life  which  are  still  influ- 
ential in  modern  thought,  but  neither  microscope  nor 
scalpel  nor  laboratory  have  revealed  the  mystery  which 
seems  ever  to  beckon  us  onward  to  another  and  entirely 
different  sphere  of  existence.  Hippocrates  invented  the 
hypothesis  of  a  principle  (<pu<ns,  or  nature)  which  influences 
the  organism  and  superintends  it  with  a  kind  of  intelli- 
gence, and  to  which  other  principles  (tuvape^  powers)  are 
subordinated  for  the  maintenance  of  various  functions. 
This  was  also  the  theory  of  Aristotle,  who  gave  the  name 
of  soul  (<f'u%y)  to  the  animating  principle. 

Paracelsus  and  the  chemical  philosophers,  from  the 
fifteenth  to  the  seventeenth  century,  maintained  that  all 
the  phenomena  of  vitality  may  be  explained  by  chemical 
laws.  To  these  succeeded  the  mathematical  school  under 
Bellini  (A.D.  1645),  who  taught  that  all  vital  functions 
may  be  explained  by  gravity  and  mechanical  impulse. 
These  theories  were  supplanted  by  those  of  the  physiolo- 
gists. Van  Helmont  revived  the  Hippocratian  idea  of  a 
specific  agent,  which  he  called  archeus.  This  was  more 
fully  elaborated  by  Stahl,  who  taught  that  by  the  opera- 


THE  MICROSCOPE  IN  BIOLOGY.          117 

tion  of  an  immaterial  animating  principle  or  soul  (anima\ 
all  vital  functions  are  produced.  The  vis  medicatrix  na- 
tures of  Cullen  was  an  attempt  to  compromise  between 
the  rival  theories  of  a  superadded  principle  and  a  special 
activity  in  organized  matter  itself.* 

Harvey,  Hunter,  Miiller,  and  Prout  proposed  hypotheses 
similar  to  those  of  Aristotle  and  Hippocrates,  and  many 
modern  scientific  men  accept  similar  views.  The  recent 
doctrine  of  the  correlation  of  physical  forces  has,  however, 
revived  the  mechanical  and  chemical  theories,  and  the 
industry  with  which  these  views  have  been  propagated 
has  gained  many  adherents. 

It  is  to  be  regretted  that  philosophy  should  assume  the 
name  of  science  and  dogmatize  under  that  appellation. 
The  object  of  science  is  to  state  facts,  and  not  to  dream, 
yet  such  is  the  nature  of  man's  intellect  that  it  will  seek 
to  account  for  facts,  and  is  thus  drawn  into  metaphysical 
speculation.  If  the  age-long  controversy  between  the 
physicists  and  the  vitalists  is  ever  to  cease,  it  will  prob- 
ably be  through  the  microscopic  demonstration  of  the 
absolute  difference  between  living  and  non-living  matter. 

In  the  present  chapter  it  is  designed  to  set  forth  briefly 
the  principal  facts  of  elementary  biology  as  they  have 
been  brought  to  light  by  microscopy.  For  further  illus- 
trations in  vegetable  and  animal  histology,  reference  may 
be  made  to  following  chapters. 

1.  All  biologists  agree  that  the  elementary  unit  in  living 
bodies  is  the  cell.  This,  according  to  the  most  recent  in- 
vestigations, is  a  soft,  transparent,  colorless,  jelly-like  par- 
ticle of  matter,  which  may  be  large  enough  to  be  just  dis- 
cernible to  the  naked  eye,  or  so  small  as  to  be  invisible 
with  our  best  instruments.  The  simplest  or  most  elemen- 
tary forms  of  vegetable  or  animal  life  consist  of  single 
cells,  while  the  more  complex  organisms  are  built  up  of 

*  Compare  Bostock's  History  of  Medicine. 


118  THE    MICROSCOPIST. 

great  numbers  of  these  cells  with  the  materials  which 
they  have  produced  and  deposited. 

Haller,  who  has  been  called  the  father  of  modern  physi- 
ology, seems  first  to  have  conceived,  though  vaguely 
(A.D.  1766),  the  idea  of  the  essential  unity  of  vital  struc- 
ture. 

In  1838,  Schleiden  and  Schwann  wrote  on  the  elemen- 
tary cell,  the  former  treating  of  the  vegetable,  and  the 
latter  of  the  animal  cell.  From  this  time  may  be  dated 
the  origin  of  the  cell  doctrine.  Much  importance  was 
assigned  to  the  distinction  between  cell-wall,  cell-con  tents, 
nuclei,  and  nucleoli. 

In  1835,  Dujardin  discovered  in  the  lower  animals  a 
contractile  substance  capable  of  movement,  to  which  he 
gave  the  name  of  sarcode. 

In  1861,  Max  Schultze  showed  that  sarcode  is  analo- 
gous to  the  body  or  contents  of  animal  cells,  and  that  on 
this  account  the  infusorial  animalcules  possessed  of  inde- 
pendent life  were  simple  or  compound. 

Examinations  of  this  structure  were  made  by  numerous 
observers,  and  the  identity  of  many  of  its  properties  in 
animals  and  vegetables  established.  To  this  structure 
the  name  of  protoplasm,  rather  than  sarcode,  has  been 
assigned.  As  this  term  has  been  somewhat  loosely  used, 
so  as  to  refer  to  it  either  in  the  dead  or  living  state,  Dr. 
Beale  has  proposed  the  term  bioplasm  for  elementary  struc- 
ture while  living,  and  has  given  a  generalization  from 
observed  facts  which  has  attracted  much  attention.  He 
distinguishes  in  all  organic  forms  three  states  of  matter: 
First.  Germinal  matter  or  bioplasm,  or  matter  which  is 
living.  Second.  Matter  which  was  living,  or  formed  mate- 
rial. Third.  Matter  about  to  become  living,  or  pabulum. 

Schleiden  and  Schwann  considered  the  cell  as  a  growth 
from  a  nucleus,  and  to  consist  of  a  cell-wall  and  cavity. 
In  vegetable  cells  there  seemed  to  be  an  external  wall  of 
cellulose,  within  which  was  another,  the  primordial  utri- 


THE    MICROSCOPE    IN    BIOLOGY.  119 

cle.  But  it  has  since  been  shown  that  the  appearance  of 
the  primordial  utricle  is  caused  by  the  protoplasm  or  bio- 
plasm lying  in  apposition  with  the  inner  surface  of  the 
cell-wall.  In  the  cryptogamia,  cells  are  known  to  occur 
in  which  no  nucleus  is  visible.  Max  Schultze  and  Hackel 
have  also  discovered  non-nucleated  forms  of  animal  life. 
The  idea  of  nucleus  and  cell-wall  as  essential  to  a  cell  is 
therefore  abandoned.  Nuclei  are  regarded  as  new  centres 
of  living  matter,  or  minute  particles  of  such  matter  capa- 
ble of  independent  existence.  Some  of  these  masses  are 
so  small  as  to  be  barely  visible  with  the  one-fiftieth  objec- 
tive under  a  magnifying  power  of  five  thousand  diameters. 

2.  The  structure  and  formation  of  a  simple  cell  may  be 
illustrated  by  Plate  V,  Figs.  85  to  89,  after  Beale.*  The 
earliest  condition  of  such  a  living  particle  is  shown  in 
Plate  Y,  Fig.  85.  If  the  external  membrane  of  a  fully 
developed  spore  or  any  of  the  growing  branches  (Plate  Yy 
Figs.  86  to  89)  be  ruptured,  such  particles  would  be  set 
free  in  vast  numbers. 

The  surface  of  such  a  particle  becomes  altered  by  con- 
tact with  external  agencies.  A  thin  layer  of  the  external 
surface  is  changed  into  a  soft  membrane  or  cell-wall, 
through  which  pabulum  passes  and  undergoes  conversion 
into  living  matter,  which  thus  increases.  The  increase 
of  size  is  not  owing  to  the  addition  of  new  matter  upon 
the  external  surface,  but  to  the  access  of  new  matter  in- 
teriorly. The  thickness  of  the  formed  material  depends 
on  external  circumstances,  as  temperature,  moisture,  etc. 
If  these  be  unfavorable  to  the  access  of  pabulum,  layer 
after  layer  of  living  matter  will  die  or  be  deposited,  as  in 
Plate  Y,  Figs.  87  and  88.  If  such  a  cell  be  exposed  to 
circumstances  favorable  to  growth,  the  accession  of  fresh 
pabulum  will  cause  portions  of  living  matter  to  make 


*  Physiological  Anatomy  and  Physiology  of  Man,  by  Drs.  Todd,  Bow- 
man, and  Beale.     New  edition. 


120  THE    MICROSCOPIST. 

their  way  through  natural  pores  or  chance  fissures  and 
protrude,  as  in  the  figures. 

3.  The  peculiar  phenomena  of  living  cells  or  bioplasms 
may  be  classified  as  follows:  Active  or  spontaneous  move- 
ment, nutrition  and  growth,  and  the  power  of  reproduc- 
tion. These  vital  actions,  according  to  Dr.  Beale,  occur 
in  the  bioplasm  only,  while  the  formed  material,  or  non- 
living matter,  is  the  seat  of  physical  and  chemical  changes 
exclusively.  Physical  processes,  as  diffusion  and  osmose, 
occur  in  bioplasmic  particles,  but  the  peculiar  phenomena 
referred  to,  and  which  are  properly  termed  vital,  do  not 
occur  in  non-living  matter. 

Movements  of  Cells. — Granules  imbedded  in  the  bioplasm, 
either  formed  material  or  accidental  products,  enable  our 
microscopes  to  observe  internal  movement,  while  change 
of  form  and  of  place  exhibit  the  movement  of  the  entire 
cell. 

The  granular  movement  is  either  vibratory  or  continu- 
ous. The  vibrations  of  the  granules  appear  similar  to  the 
molecular  movement  described  by  Dr.  Robert  Brown  in 
1827,  and  which  is  common  to  all  small  masses  of  matter, 
organic  or  inorganic.  Minute  cells  may  thus  dance  in 
fluid  as  well  as  fine  powders,  etc.  Such  movements  occur, 
however,  in  the  interior  of  living  cells,  and  may  possibly 
be  connected  with  vitality.  In  the  salivary  corpuscles, 
the  dancing  motion  ceases  on  the  addition  of  a  solution 
of  one-half  to  one  per  cent,  of  common  salt,  while  such 
addition  has  no  influence  of  the  kind  on  fresh  pus  or 
lymph. 

The  continuous  granular  motion  is  either  a  relatively 
slow  progression,  corresponding  to  the  change  of  form  in 
the  cell,  or  a  swifter  flowing  movement.  Max  Schultze 
thus  describes  this  motion  in  the  threads  of  sarcode  pro- 
jected from  the  apertures  of  a  Foraminiferal  shell:  "  As 
the  passengers  in  a  broad  street  swarm  together,  so  do 
the  granules  in  one  of  the  broader  threads  make  their 


PLATE  V. 


FIG.  85. 


Minute  particles  of  Bioplasm.   From 
Mildew,   sVth  in.  Obj. 


FIG.  88. 


Passage  of  Germinal-matter  through 
pores  in  the  formed  material.    X  1800. 


FIG.  86. 


FIG.  89. 


m 


Production  of  formed-material  on 
surface  of  Bioplasm.    X  1800. 


Production  and  accumulation  of 
Formed-material  on  Bioplasm.  Epi- 
thelium of  cuticle.  X  700. 


FIG.  87. 


FIG.  90. 


Further  production  of  formed- 
material.  At  a  is  the  budding 
Bioplasm,  passing  through  pores 
in  the  formed-material.  X  1800. 


Amoebce  from  organic  infusion. 


THE  MICROSCOPE  IN  BIOLOGY.          121 

way  by  one  another,  oftentimes  stopping  and  hesitating, 
yet  always  pursuing  a  determinate  direction  correspond- 
ing to  the  long  axis 'of  the  thread.  They  frequently  be- 
come stationary  in  the  middle  of  their  course,  and  then 
turn  round,  but  the  greater  number  pass  to  the  extreme 
end  of  the  thread,  and  then  reverse  the  direction  of  their 
movement."  No  physical  or  chemical  action  with  which 
we  are  acquainted  will  account  for  such  motions,  which 
have  no  analogy  in  unorganized  bodies. 

Changes  of  form  are  most  strongly  marked  in  the  lower 
forms  of  animal  life,  although  occurring  also  in  the  sim- 
pler vegetables,  as  the  volvox.  The  Amoeba  or  Proteus  is 
typical  of  such  changes,  which  have  hence  been  termed 
Amoeboid  (Plate  V,  Fig.  90).  When  an  Amoeba  meets 
another  animal  which  is  too  slow  to  escape,  it  sends  out 
projections  which  encircle  its  prey;  these  coalesce,  and 
invest  the  whole  mass  with  its  bioplasm.  It  maintains 
its  grasp  till  it  has  abstracted  all  the  portions  which  are 
soluble,  and  then  relaxes  its  hold. 

Amoeboid  cells  in  higher  animals  rarely  move  so  rapidly 
as  the  Amoeba  itself.  Their  motions  are  limited  to  a 
gradual  change  of  form  or  to  the  protrusion  of  processes 
in  the  form  of  threads,  or  tuberosities,  or  tufts,  which 
either  drag  the  rest  of  the  body  after  them  or  are  again 
withdrawn. 

Cells  of  bioplasm  rnay  not  only  change  their  form,  but 
may  wander  from  place  to  place  by  protruding  a  portion 
of  their  mass,  which  drags  the  rest  after  it.  The  discov- 
ery of  wandering  cells  in  the  higher  organisms,  as  man, 
has  opened  quite  a  new  and  important  field  of  physiologi- 
cal and  pathological  research. 

The  movements  of  bioplasm  may  be  changed,  acceler- 
ated, retarded,  or  stopped  by  a  variety  of  stimuli,  mechani- 
cal, electrical,  chemical,  and  nervous.  Gentle  warmth  and 
moisture  are  necessary  to  their  perfection.* 

*  See  Strieker's  Manual  of  Histology. 


122  THE    MICROSCOPIST. 

The  nutrition  and  growth  of  the  living  cell  has  already 
been  described  as  the  conversion  of  pabulum  into  bioplasm 
or  living  matter.  The  subject  of  reproduction  will  be  ex- 
amined below  under  the  head  of  cell-genesis. 

4.  The  microscopic  demonstration  of  bioplasm   may   be 
effected  by  the  use  of  an  alkaline  solution  of  coloring 

'matter,  as  carmine.  (See  Chapter  Y.)  As  bioplasm  pos- 
sesses an  acid  reaction,  the  alkali  is  neutralized  and  the 
color  retained.  This  process,  however,  is  rather  a  dem- 
onstration of  the  protoplasm  which  was  recently  alive. 
For  living  cells  or  bioplasm,  we  must  depend  on  supplying 
them  artificially  with  colored  food.  Thus  indigo,  carmine, 
etc.,  in  fine  particles,  added  to  the  pabulum  of  cells  or 
liquid  media  in  which  they  float,  will  be  taken  into  the 
interior  of  the  bioplasm  by  the  nutritive  process.  In  this 
way  Recklinghausen  showed  the  migration  of  pus-corpus- 
cles. 

"Welcker  and  Osborne  were  the  first  to  use  a  solution 
of  carmine  in  order  to  stain  the  nuclei  of  tissues.  They 
were  followed  by  Gerlach  and  Beale,  the  latter  of  whom 
has  greatly  improved  the  process  and  shown  its  signifi- 
cance. 

5.  The  chemistry  of  cells  and  their  products  is  an  essential 
part  of  biology,  but  would  lead  us  too  far  from  our  subject 
to  discuss,  yet  a  few  points  may  not  be  irrelevant. 

The  chemical  composition  of  bioplasm  consists  essen- 
tially of  oxygen,  hydrogen,  nitrogen,  and  carbon.  Other 
elements  are  often  present  and  important,  but  not  essen- 
tial. Of  the  relation  of  these  elements  we  know  nothing, 
save  that  they  are  in  a  state  of  constant  vibration  or 
change.  Dr.  Beale  considers  it  doubtful  if  ordinary  chemi- 
cal combination  is  possible  while  the  matter  lives.  Analy- 
sis in  the  laboratory  is  only  possible  with  the  compounds 
resulting  from  the  death  of  the  cell. 

When  living  or  germinal  matter  is  converted  into  formed 
material,  a  combination  of  its  elements  takes  place,  often 


THE  MICROSCOPE  IN  BIOLOGY.          123 

with  very  complex  results,  the  nature  of  which  has  hitherto 
baffled  the  efforts  of  chemists  to  determine.  When  the 
life  of  germinal  matter,  however,  is  suddenly  destroyed, 
or  rather  when  the  matter  is  first  transformed,  the  com- 
pounds resulting  from  various  species  have  similar  chemi- 
cal composition  and  properties,  and  an  acid  reaction  is 
developed.  Fibrin,  albumen,  water,  and  certain  salts  may 
thus  be  obtained  from  every  kind  of  germinal  matter. 
Fatty  matters  also  result,  which  continue  to  increase  in 
quantity  for  some  time  after  death.  In  slow  molecular 
death,  a  certain  amount  of  oxygen  is  taken  into  combina- 
tion, which  gives  rise  to  different  results  from  those  which 
occur  when  life  is  suddenly  destroyed.  Still  other  com- 
binations are  due  to  vital  actions  which  are  not  yet  under- 
stood. Thus  some  bioplasm  produces  muscle;  other  par- 
ticles originate  nerve  structure,  cartilage, bone,  connective 
tissue,  etc.  Many  chemical  changes  occur  also  in  formed 
material  after  its  production.  It  may  become  dry  or  fluid, 
or  split  up  into  gaseous  or  soluble  substances  as  soon  as 
produced.  Imperfect  oxidation  may  lead  to  the  formation 
of  fatty  matters,  uric  acid,  oxalates,  sugar,  etc.  At  the 
earliest  period  of  development,  the  formed  material  con- 
sists principally  of  albuminous  and  fatty  matters,  with 
chlorides,  alkaline  and  earthy  phosphates.  At  a  later 
period  gelatin,  with  amyloid  or  starchy  matter,  is  pro- 
duced.* 

6.  Varieties  in  the  form  and  Function  of  Bioplasm.. — 
Mutability  of  shape  is  characteristic  of  amoeboid  cells, 
and  no  conclusions  can  be  drawn  from  their  appearance 
after  death.  Where  numbers  of  them  are  accumulated, 
they  are  flattened  by  mutual  pressure  so  as  to  appear 
polyhedral,  laminated,  or  prismatic.  The  upper  layers  of 
laminated  epithelium  are  usually  flattened.  Where  cells 
line  the  interior  of  cavities  in  a  single  layer,  they  form 

*  See  Physiological  Anatomy,  by  Todd,  Bowman,  and  Beale. 


124  THE    MICROSCOPIST. 

plates  of  different  shape  (endothelial  cells),  or  cells  in  which 
the  long  axis  predominates  (cylindrical  epithelium),  or 
forms  which  are  intermediate  between  plates  and  cylin- 
ders. Some  cells  appear  ramified  or  stellate,  as  in  the 
cells  from  the  pith  of  a  rush,  bone-cells,  and  corpuscles  of 
the  cornea.  Others  may  become  extraordinarily  elongated, 
as  in  the  formation  of  fibre,  muscle,  etc.  Some  cells  are 
provided  with  cilia,  which  are  limited  to  one  portion  of 
the  surface,  and  project  their  free  extremities  into  the 
cavity  which  they  line.  Dr.  Beale  considers  the  cilia  to 
be  formed  material,  and  their  movements  not  vital,  but  a 
result  of  changes  consequent  on  vital  phenomena. 

Every  living  organism,  plant,  animal,  or  man,  begins 
its  existence  as  a  minute  particle  of  bioplasm.  Every 
organic  form,  leaves,  iiowers,  shells,  and  all  varieties  of 
animals ;  and  every  tissue,  cellular,  vesicular,  hair,  bone, 
skin,  muscle,  and  nerve,  originates  by  subdivision  and 
multiplication  and  change  of  bioplasm,  and  the  trans- 
formation or  metamorphosis  of  bioplasm  into  formed  ma- 
terial. It  is  evident,  therefore,  that  there  are  different 
kinds  of  bioplasm  indistinguishable  by  physics  and  chem- 
istry, but  endowed  with  different  powers.* 

7.  Cell-Genesis. — Schleiden  first  showed  that  the  em- 
bryo of  a  flowering  plant  originates  in  a  nucleated  cell, 
and  that  from  such  cells  all  vegetable  tissues  are  devel- 
oped. The  original  cells  were  formed  in  a  p&sma  or  blas- 
tema, commonly  found  in  pre-existing  cells,  the  nuclei  first 
appearing  and  then  the  cell-membrane.  These  views  were 
applied  by  Schwann  to  animal  structure.  The  latter  be- 
lieved that  the  extra-cellular  formation  of  cells,  or  their 
origin  in  a  free  blastema,  was  most  frequent  in  animals. 
The  researches  of  succeeding  physiologists  have,  however, 
led  to  a  general  belief  that  all  cells  originate  from  other 
cells. 

*  Beale's  Bioplasm. 


THE  MICROSCOPE  IN  BIOLOGY.          125 

The  doctrine  of  spontaneous  generation  or  aUogenesis 
has  been  the  object  of  considerable  research,  but  the  bril- 
liant experiments  of  Pasteur  have  shown  that  when  all 
access  of  living  organisms  into  fluids  is  prevented,  no  de- 
velopment of  such  organisms  can  be  proved  in  any  case 
to  occur.  If  the  access  of  air,  for  instance,  to  a  liquid 
which  has  been  boiled,  is  filtered  through  a  plug  of  cotton- 
wool, no  living  forms  will  appear  in  the  liquid,  but  on 
examination,  such  forms  will  be  found  in  considerable 
numbers  in  the  cotton-wool,  proving  the  presence  of  these 
forms  or  their  germs  in  the  external  air.  Recent  experi- 
ments also  render  it  probable  that  some  cell-germs  are 
indestructible  by  a  heat  far  exceeding  that  of  boiling 
water. 

There  are  three  forms  of  cell-multiplication,  by  fission, 
by  germination  or  budding,  and  by  internal  division.  The 
latter  mode  is  termed  endogenous.  In  it  new  cells  are 
produced  within  a  parent-cell  by  the  separation  of  the 
bioplasm  into  a  number  of  distinct  masses,  each  of  which 
may  become  a  new  cell,  as  in  the  fecundated  ovum. 

Fission,  or  the  division  by  cleavage  of  a  parent-cell- into 
two  or  four  parts,  may  be  regarded  as  a  modification  of 
endogenous  cell-multiplication.  A  good  example  of  it 
may  be  seen  in  cartilage. 

Budding  or  germination  consists  in  the  projection  of  a 
little  process  or  bud  from  the  mass  of  bioplasm,  which  is 
separated  by  the  constriction  of  its  base,  and  becomes  an 
independent  cell. 

8.  Reproduction  in  the  higher  organisms  consists  essen- 
tially of  the  production  of  two  distinct  elements,  a.  germ- 
cell  or  ovum,  and  a  sperm-cell  or  spermatozoid,  by  the 
contact  of  which  the  ovum  is  enabled  to  develop  a  new 
individual.  Sometimes  these  elements  are  produced  by 
different  parts  of  the  same  organism,  in  which  case  the 
sexes  are  said  to  be  united,  and  the  individual  is  called 
hermaphrodite,  androgynous,  or  monoecious.  In  other  in- 


126  THE    MICROSCOPIST. 

stances  the  sexes  are  distinct,  and  the  species  are  called 
dioecious. 

9.  The  alternation  of  generations  is  a  term  given  in  bi- 
ology to  express  a  form  of  multiplication  which  occurs  in 
some  of  the  more  simple  forms  of  life.     It  consists  really 
of  the  alternation  of  a  true  sexual  generation  with  the 
phenomenon  of  hudding.     Thus  a  fern  spore  gives  rise,  by 
budding  and  cell-division,  to  a  prothallium ;  this  produces 
archegonia  and  antheridia,  as  the  sexual  elements  are 
called,  and  the  embryo  which  results  from  sexual  union 
produces  not  a  prothallium  but  a  fern.     This  phenomenon 
is  better  seen  in  the  Hydrozoa.     In  these  the  egg  produces 
a  minute,  ciliated,  free-swimming  body,  which  attaches 
itself,  becomes  tapering,  develops  a  mouth  and  tentacles, 
and  is  known  as  the  Hydra  tuba.     This  multiplies  itself, 
and  produces  extensive  colonies  by  germination,  but  under 
certain  circumstances   divides   by   fission   and   produces 
Medusce,  which  develop  ova. 

10.  Parthenogenesis  designates  the  production  of  new 
individuals  by  virgin  females  without  the  intervention  of 
a  male.     It  has  also  been  applied  to  germination  and 
fission  in  sexless  beings.     In  the  Aphides,  ova,  are  hatched 
in  spring,  but  ten  or  more  generations  are  produced  vi- 
viparously  and  without  sexual  union  throughout  the  sum- 
mer.    In  autumn,  however,  the  final  brood  are  winged 
males  and  wingless  females,  from  whose  union  ova  are 
produced  in  the  ordinary  manner. 

11.  Transformation  and  metamorphosis  relate  to  certain 
changes  or  variations  of  development  in  the  structure  and 
life  history  of  an  individual.     Thus  an  insect  is  an  egg  or 
ovum,  a  caterpillar  or  larva,  a  pupa  or  chrysalis,  and  an 
imago  or  perfect  insect,  and  these  changes  of  condition 
and  structure  constitute  its  development.    Much  difficulty 
is  caused  by  the  phenomena  of  metamorphosis  in  assign- 
ing the  place  of  different  species,  transformations  being 
often  mistaken  for  specific  differences.     It  was  formerly 


THE    MICROSCOPE    IN    BIOLOGY.  127 

supposed  that  every  animal  passed  through,  in  its  devel- 
opment, a  series  of  stages  in  which  it  resembled  the  infe- 
rior members  of  the  animal  scale,  and  systems  of  zoology 
were  proposed  to  be  founded  on  this  dream  of  embryology. 
Careful  research,  however,  has  shown  that  larval  changes 
present  many  variations.  In  some  the  young  exhibit  the 
conditions  of  adults  of  lower  animals.  Thus  the  Eolis,  a 
univalve  shell  fish,  in  its  young  state  has  all  the  charac- 
teristics of  a  Pteropod,  a  free-swimming  mollusk.  Some- 
times development  is  retrograde,  and  the  adult  is  a  de- 
graded form  as  compared  with  the  larva,  thus  setting  at 
nought  all  our  theories,  and  teaching  us  that  it  is  better 
to  observe  than  to  imagine. 

12.  Discrimination  of  Living  Forms. — We  have  seen, 
section  6,  that  there  are  different  kinds  of  living  matter 
endowed  with  different  powers.  We  have  also  seen,  sec- 
tion 7,  how  varied  are  the  forms  of  multiplication.  Yet 
when  we  come  to  discriminate  between  animal  and  vege- 
table life,  we  find  it  exceedingly  difficult,  especially  in 
their  more  simple  forms.  Neither  form,  nor  chemical 
composition,  nor  structure,  nor  motive  power,  affords  suf- 
ficient grounds  for  discrimination.  Yet  when  we  consider 
the  functions  of  bioplasm  in  its  varied  forms,  we  may  con- 
veniently group  all  living  beings  in  three  great  divisions, 
viz.,/im#i,  plants,  and  animals. 

The  bioplasm  of  the  plant  finds  its  pabulum  in  merely 
inorganic  compounds,  while  that  of  the  animal  is  prepared 
for  it,  directly  or  indirectly,  by  the  vegetable.  The  func- 
tion of  fungi  appears  to  be  the  decomposition  of  the  formed 
material  of  plants  and  animals  by  the  means  of  fermenta- 
tion or  putrefaction,  since  these  latter  processes  are  depen- 
dent on  the  presence  of  fungi.  Thus  by  bioplasm  are  the 
structures  of  plants  and  animals  reared  from  inorganic 
materials,  and  by  bioplasm  are  they  broken  down  and 
restored  to  the  inanimate  world. 


128  THE    MICROSCOPIST. 

CHAPTER    X. 

THE   MICROSCOPE   IN   VEGETABLE   HISTOLOGY   AND   BOTANY. 

HISTOLOGY  (from  faros,  a  tissue)  treats  of  formed  mate- 
rial, or  the  microscopic  structure  resulting  from  the  trans- 
formation of  germinal  or  living  matter.  The  nature  of 
this  transformation  is  partly  physical  and  partly  vital, 
and,  as  already  stated,  is  often  so  complex  as  to  baffle  all 
chemical  analysis.  Some  light,  however,  has  been  thrown 
on  this  subject  by  the  modification  of  ordinary  crystalline 
forms  when  inorganic  particles  aggregate  in  the  presence 
of  certain  kinds  of  organic  matter.  To  this  mode  of  form- 
ation the  name  of  molecular  coalescence  has  been  given. 
Mr.  Rainey  and  Professor  Harting  contemporaneously 
experimented  with  solutions  of  organic  colloids,  and  found 
that  the  crystallization  of  certain  lime  salts,  as  the  car- 
bonate, was  so  modified  by  such  solutions  as  to  resemble 
many  of  the  calcareous  deposits  found  in  nature.  These 
researches  leave  little  doubt  but  that  a  majority  of  calca- 
reous and  silicious  organic  forms  may  be  thus  accounted 
for.  Such  changes  are  rather  physical  than  vital. 

Cell-substance  in  Vegetables. — The  protoplasm  or  bio- 
plasm in  vegetable-cells  cannot  be  distinguished  from  ani- 
mal usarcode"  or  protoplasm  except  by  the  nature  of  the 
pabulum  or  aliment  necessary  to  its  nutrition.  The  vege- 
table, under  the  stimulus  of  light,  decomposes  carbonic 
acid,  and  acquires  a  red  or  green  color  from  the  compounds 
which  it  forms,  while  the  animal  requires  nutriment  from 
pre-existing  organisms.  Yet  this  definition  fails  to  apply 
to  fungi,  which  resemble  primitive  animals  even  in  this 
respect.  So  difficult  is  it  to  discriminate  that  the  simpler 
forms  of  vegetables  have  often  been  classed  by  naturalists 
among  animals,  and  vice  versd.  Amoeboid  movements 
have  been  observed  in  the  bioplasm  of  vegetable-cells, 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      129 

especially  in  the  Volvox,  and  some  have  considered  it 
probable  that  an  organism  may  live  a  truly  vegetable  life- 
at  one  period  and  a  truly  animal  life  at  another. 

Analogous  to  amoeboid  movements,  is  the  motion  of 
bioplasmic  fluid  in  the  interior  of  undoubtedly  vegetable 
cells.  This  movement  is  called  cydosis,  and  may  be  de- 
tected under  the  microscope  by  the  granules  or  particles 
which  the  current  carries  with  it  in  the  transparent  cells 
of  Chara,Vallisneria,  etc.,  and  in  the  epidermic  hairs  of 
many  plants,  as  Tradescantia,  Plantago,  etc.  (Plate  VI,, 
Fig.  91). 

The  bioplasm  of  plants  may  be  stained  with  carmine 
solution  without  affecting  the  cell-wall  or  other  formedi 
material. 

Cell-wall  or  Membrane. — Plants,  whether  simple  or 
complicated  in  structure,  are  but  cells  or  aggregations  of 
cells.  In  the  simplest  vegetables  or  Protophytes,  each  cell 
lives  as  it  were  an  independent  life,  performing  every 
function;  while  in  the  higher  plants,  as  the  palm  or  oak, 
the  cells  undergo  special  modifications,  and  serve  various 
functions  subsidiary  to  the  life  of  the  plant  as  a  whole. 

Cell-membrane,  or  the  envelope  of  formed  material,  was 
formerly  thought  to  be  composed  of  two  layers,  to  the 
inner  one  of  which  the  name  of  primordial  utricle  was 
given,  but  this  is  now  considered  to  be  but  the  external 
surface  of  the  bioplasm  or  germinal  matter. 

The  chemical  nature  of  cell-membrane  is  nearly  identi- 
cal with  starch,  being  composed  of  cellulose.  The  presence 
of  cellulose  may  be  shown  by  the  blue  color  which  is 
produced  by  applying  iodine  and  sulphuric  acid,  or  the 
iodized  solution  of  chloride  of  zinc. 

Endosmose  will  take  place  in  cell-membrane,  allowing 
solutions  to  pass  through,  as  pabulum,  and  the  manner  of 
this  passage  may  in  some  instances  determine  the  subse- 
quent deposit  of  formed  material.  Sometimes  actual  pores 
are  left  in  the  membrane,  as  in  Sphagnum  (Plate  VI,  Fig. 


130  THE    MICROSCOPIST. 

92).  The  walls  of  vegetable-cells  are  often  thickened  by 
deposit.  If  this  is  in  isolated  patches,  the  cells  are  called 
dotted  (Plate  VI,  Fig.  93),  and  it  is  sometimes  difficult  to 
distinguish  them  from  porous  cells.  Many  cells  have  a 
spiral  fibre  (Plate  VI,  Fig.  94),  which  appears  to  have 
been  detached  from  the  outer  membrane.  In  the  seeds  of 
Collomia,  etc.,  the  cell-wall  is  less  consolidated  than  the 
deposit,  so  that  on  softening  the  cells  by  water,  the  spiral 
fibres  suddenly  spring  out,  making  a  beautiful  object  for 
a  half-inch  object-glass  (Plate  VI,  Fig.  95). 

The  tendency  of  formed  material  to  arrange  itself  in  a 
spiral  is  seen  in  the  endochrome  of  many  of  the  simpler 
plants,  as  Zygnema,  and  the  cell-wall  sometimes  tears  most 
readily  in  a  spiral  direction. 

If  the  spiral  deposit  is  broken  and  coalesces  at  some  of 
its  turns,  it  forms  an  annulus  or  ring.  Some  cells  show 
both  rings  and  spirals. 

For  the  production  of  a  spiral  movement  or  growth, 
another  force  is  needed  in  addition  to  the  centripetal  and 
centrifugal  forces  which  are  necessary  for  curvilinear  mo- 
tion. The  centripetal  point  must  be  carried  forward  in 
space  by  a  progressive  force.  When  we  consider  that  a 
spiral  form  is  so  frequently  seen  in  morphology,  that  the 
secondary  planets  move  in  spirals  round  their  primaries, 
and  that  even  in  distant  nebulae  the  same  law  prevails, 
we  are  struck  with  the  unity  of  plan  which  is  exhibited 
throughout  the  universe,  and  can  scarcely  fail  to  observe 
that  even  a  microscopic  cell  shows  the  tracings  of  the  same 
divine  handiwork  which  swings  the  stars  in  their  courses. 

Sderogen — Ligneous  Tissue.  —  Sometimes  the  deposit 
within  the  cell-wall  is  of  considerable  thickness,  and  often 
in  concentric  rings,  through  which  a  series  of  passages  is 
left  so  that  the  outer  membrane  is  the  only  obstacle  to 
the  access  of  pabulum,  as  in  the  stones  of  fruit,  gritty  tis- 
sue of  the  pear,  etc.  (Plate  VII,  Fig.  96).  The  nature  of 
this  deposit  is  similar  to  cellulose,  although  often  contain- 


PLATE  VI. 


FIG.  91. 


FIG.  93. 


Dotted  cells— pith  of  Elder. 


Fio.  94. 


Circulation  of  fluid  in  hairs  of  Tradescantia 
Virginica. 


Spiral  cells  : — A,  Balsam  ;  B,  c, 
Pleurothallis. 


FIG.  92. 


FIG.  95. 


Portion  of  the  leaf  of  Sphagnum. 


Spiral  fibres  of  seed-coat  of  Collomia. 


THE    MICB.OSCOPE    IN    HISTOLOGY    AND    BOTANY.       131 

ing  resinous  and  other  matters.  Woody  fibre  or  ligneous 
tissue  is  quite  similar,  save  that  the  cells  have  become 
elongated  or  fusiform,  and  when  completely  filled  up  with 
internal  deposit,  fulfil  no  other  purpose  than  that  of  me- 
chanical support  (Plate  VII,  Fig.  97).  The  woody  fibres 
of  the  Coniferce  exhibit  peculiar  markings,  which  have 
been  called  glandular  (Plate  VII,  Fig.  98).  In  these  the 
inner  circle  represents  a  deficiency  of  deposit  as  in  other 
porous  cells,  while  the  outer  circle  is  the"  boundary  of  a 
lenticular  cavity  between  the  adjacent  cells.  This  ar- 
rangement is  so  characteristic  as  to  enable  us  to  determine 
the  tribe  to  which  a  minute  fragment,  even  of  fossil  wood, 
belonged. 

Spiral  Vessels. — If  spiral  cells  are  elongated,  or  coalesce 
at  their  ends,  they  become  vessels,  some  of  which  convey 
air  and  some  fluid  (Plate  VII,  Fig.  99).  As  in  cells,  the 
want  of  continuity  in  the  spiral  fibre  sometimes  produces 
rings,  when  the  duct  is  called  annular.  In  other  instances 
the  spires  are  still  more  broken  up  by  the  process  of  growth, 
so  as  to  form  an  irregular  network  in  the  duct,  which  is 
then  said  to  be  reticulated.  A  still  greater  variation  in 
the  deposit  produces  dotted  ducts.  Not  infrequently  we 
find  all  forms  in  the  same  bundle  of  vessels. 

Laticiferous  Vessels  (Plate  VII,  Fig.  100).— These  con- 
vey the  milky  juice  or  latex  of  such  plants  as  possess  it, 
as  the  Euphorbiacese,  india-rubber  plant,  etc.,  and  differ 
from  the  ducts  above  described  by  their  branching,  so  as 
to  form  a  network,  while  ducts  are  straight  and  parallel 
with  each  other. 

The  laticiferous  vessels  resemble  the  capillary  vessels  of 
animals,  while  the  spiral  ducts  remind  us  of  the  trachea 
of  insects. 

Siliceous  Structures. — The  structures  of  many  plants, 
especially  the  epidermis,  often  become  so  permeated  with 
a  deposit  of  silica,  that  a  complete  skeleton  is  left  after 
the  soft  vegetable  matter  is  destroyed.  The  frustules  of 


132  THE    MICROSCOPIST. 

Diatoms  have  in  this  way  been  preserved  in  vast  numbers 
in  the  rocky  strata  of  the  earth.  The  markings  on  these 
siliceous  shells  are  so  delicate  as  to  be  employed  as  a  test 
of  microscopic  power  aud  definition.  In  a  species  of 
Equisetum  or  Dutch  rush,  silica  exists  in  such  abundance 
that  the  stems  are  sometimes  employed  by  artisans  as  a 
substitute  for  sand-paper.  If  such  a  stem  is  boiled  and 
macerated  in  nitric  acid  until  all  the  softer  parts  are  de- 
stroyed, a  cast  of  pure  silica  will  exhibit  not  only  the 
forms  of  the  epidermic  cells,  but  details  of  the  stomata  or 
pores.  The  same  also  is  true  of  the  husk  of  a  grain  of 
wheat,  etc.,  in  which  even  the  fibres  of  the  spiral  vessels 
are  silicified.  The  stellate  hairs  of  the  siliceous  cuticle 
from  the  leaf  of  Deutzia  scabra  forms  a  beautiful  polari- 
scope  object. 

FORMED  MATERIAL  WITHIN  VEGETABLE  CELLS. 

1.  Raphides. — These  are  crystalline  mineral  substances, 
principally  oxalate,  citrate,  and  phosphate  of  lime.     They 
occur  in  all  parts  of  the  plant,  sometimes  in  the  form  of 
bundles  of  delicate  needles,  sometimes  in  larger  crystals, 
and  sometimes  in  stellate  or  conglomerate  form.     Mr.  E. 
Quekett  produced  such  forms  artificially  by  filling  the 
cells  of  rice-paper  with  lime  water  under  an  air-pump,  aud 
then  placing  the  paper  in  weak  solutions  of  phosphoric  or 
oxalic  acid. 

2.  Starch. — This  performs  in  plants  a  similar  function 
to  that  of  fat  in  animals,  and  is  a  most  important  ingre- 
dient in  human  food,  since  two-thirds  of  mankind  subsist 
almost  exclusively  upon  it.     It  is  found  in  the  cells  of 
plants  in  the  form  of  granules  or  secondary  cells.     Each 
granule  under  the  microscope  shows  at  one  extremity  a 
circular  spot  or  hilum,  around  which  are  a  number  of 
curved  lines,  supposed  to  be  wrinkles  in  the  cell-membrane. 
When  starch  is  boiled  in  water,  this  membrane  bursts  and 


PLATE  VII. 


Gritty  tissue— Pear. 


Spiral  vessels: — A,  reticulated;  B,  old 
vessel,  with  perforations;  c,  D,  spiral 
vessels,  becoming  annular. 


FIG.  97. 


FIG. 100. 


Wood-fibre-flax. 


Lactiferous  vessels. 


FIG.  98. 


FIG. 101. 


Section  of  Coniferous  Wood  in  the 
direction  of  the  fibres. 


Cubical  parenchyma,  with  stellate  cells, 
from  petiole  of  Nuphar  lutea. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       133 

the  amylaceous  matter  is  dissolved.  Iodine  stains  starch 
blue.  Starch  shows  in  the  polariscope  a  black  cross  in 
each  grain,  changing  to  white  as  the  prism  is  revolved. 

3.  Chlorophyll  is  the  green  coloring  matter  of  plants. 
It  is  usually  seen  in  the  form  of  granules  of  bioplasm  in 
the  interior  of  cells.     These  green  granules  yield  their 
chlorophyll  to  alcohol  and  ether.     It  seems  to  be  neces- 
sary to  nutrition,  since  green  plants  under  the  stimulus 
of  light  break  up  carbonic  acid  into  oxygen  and  carbon, 
the  latter  of  which  is  absorbed. 

The  red  and  yellow  color  of  autumn  leaves  is  owing  to 
the  chemical  metamorphosis  of  chlorophyll,  as  also  is  the 
red  color  of  many  of  the  lower  Algse,  etc.  In  the  latter 
it  seems  to  be  in  some  way  connected  with  the  vital  pro- 
cesses. 

4.  The  coloring  matter  of  flowers  is  various,  and  ordinarily 
depends  on  the  colored  fluid  contained  in  cells  subjacent 
to  the  epidermis,  although  sometimes  it  is  in  the  form  of 
solid  corpuscles.    White  patches  on  leaves,  etc.,  arise  from 
absence  of  chlorophyll. 

5.  Milky  juices  are  true  secretions  contained  in  the  lati- 
ciferous  ducts.     The  juice  of  the  dandelion,  caoutchouc 
or  india-rubber,  which  is  the  concrete  juice  of  the  Ficus 
elastica,  and  gutta-percha,  from  Isonandra  gutta,  are  exam- 
ples. 

6.  Fixed  oils  are  found  in  the  cells  of  active  tissues,  and 
notably  in  seeds,  where  they  serve  to  nourish  the  embryo. 
Cocoanut,  palm,  castor,  poppy,  and  linseed  oils  are  exam- 
ples. 

7.  Volatile  oil,  sometimes  called  essential  oil,  is  chiefly 
found   in   glandular   cells   and   hairs   of   the   epidermis. 
Many  of  them  yield  a  resinous  substance  by  evaporation. 

8.  Camphor  is  analogous  to  volatile  oil,  although  solid 
at  ordinary  temperatures.     It  abounds  in  the  Lauracese. 

9.  Resin,  wax,  and  tallow  are  also  found  in  plants.     The 
bloom  of  the  plum  and  grape  is  due  to  wax. 


134  THE    MICROSCOPIST. 

10.  Gum  is  a  viscid  secretion.  What  is  called  gum 
tragacanth,  is  said  to  be  partially  decomposed  cell-mem- 
brane, and  is  allied  to  amyloid  matter. 

Forms  of  Vegetable  Cells. — From  the  account  given  in 
the  chapter  on  biology,  page  123,  it  is  evident  that  the 
form  of  cells  is  quite  varied,  and  often  depends  on  the 
amount  of  pressure  from  aggregation,  yet  function  also 
has  much  to  do  in  the  determination  of  shape.  Thus 
while  most  elongated  cells  are  lengthened  in  the  direction 
of  plant-growth,  in  which  is  least  resistance,  the  medul- 
lary rays  of  Exogenous  stems  are  elongated  in  a  horizon- 
tal direction.  Some  cells  are  cubical,  as  in  the  leaves  of 
the  yellow  water-lily,  Nuphar  lutea  (Plate  VII,  Fig.  101). 
Others  are  stellate,  as  in  the  rush  (Plate  VIII,  Fig.  102). 
In  many  tissues  are  large  cavities  or  air-chambers  alto- 
gether void  of  cells,  and  in  leaves  such  cavities  communi- 
cate with  the  external  air  by  means  of  stomata  or  pores 
(Plate  VIII,  Fig.  103),  which  are  usually  provided  with 
peculiar  cells  for  contracting  or  widening  the  orifice. 

The  Botanical  Arrangement  of  Plants. — Considered  with 
reference  to  their  general  structure,  plants  are  divided  by 
botanists  into  cellular  and  vascular.  The  first  of  these 
classes  is  of  greatest  interest  to  the  microscopist,  as  em- 
bracing the  minuter  forms  of  vegetable  life. 

The  classification  and  natural  grouping  of  plants  is  yet 
far  from  being  perfect,  although  microscopic  examinations 
have  largely  contributed  to  an  orderly  arrangement  of  the 
multitudinous  varieties  in  this  field  of  research.  In  the 
present  work  we  propose  only  a  brief  outline  of  typical 
subjects  of  interest,  with  the  methods  of  microscopic  ex- 
amination. 

Fungi. — At  page  127  it  was  stated  that  all  living  beings 
may  be  grouped  in  three  divisions,  fungi,  plants,  and 
animals.  Botanists  generally  class  fungi  among  cellular 
flowerless  plants.  They  cannot  assimilate  inorganic  food 
as  other  plants,  but  live  upon  the  substance  of  animal  or 


PLATE  VIII. 


FIG.  102. 


Section  of  cellular  parenchyma  of  Rush. 


Portion  of  the  cuticle  of  the  leaf  of  the  Iris 
Germanica,  torn  from  its  surface. 


FIG.  104. 


Cells  from  the  petal  of  the  Geranium 
( Pelargonium ). 


^Cuticle  of  leaf  of  Indian  Corn  (Zeamais). 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      135 

vegetable  tissue.  They  also  differ  from  ordinary  vegeta- 
bles by  the  total  absence  of  chlorophyll  or  its  red  modifi- 
cation. A  large  number  of  this  strange  class  are  micro- 
scopic, and  require  high  powers  for  their  observation. 
Recent  investigations  show  that  individual  fungi  are  de- 
veloped iu  very  dissimilar  modes,  and  are  subject  to  a 
great  variety  of  form,  rendering  it  probable  that  those 
which  seem  most  simple  are  but  imperfectly  developed 
forms.  Amoeboid  motions  also  in  the  cell-substance  of 
certain  kinds  of  fungi,  and  the  projection  of  threads  of 
bioplasm,  show  a  great  resemblance  to  some  of  the  lower 
forms  of  animal  life,  as  the  Rhizopods. 

All  fungi  exhibit  two  well-defined  structures,  a  myce- 
lium or  vegetative  structure,  which  is  a  mass  of  delicate 
filaments  or  elongated  cells ;  arid  a  fruit  or  reproductive 
structure,  which  varies  in  different  tribes.  In  Torula,  one 
or  more  globular  cells  are  produced  at  the  ends  of  fila- 
ments composed  of  elongated  cells;  these  globules  drop 
off  and  become  new  mycelia.  The  "  yeast  plant,"  or  Torula 
cerevisia  (Plate  IX,  Fig.  107),  receives  its  name  from  its 
habitat.  Fermentation  depends  upon  its  presence,  as  pu- 
trefaction does  upon  the  minute  analogous  bodies  called 
Bacteria  and  Vibriones.  Bacteria  are  minute,  moving, 
rod-like  bodies,  sometimes  jointed  ;  and  vibriones  are 
moniliform  filaments,  having  a  vibratile  or  wriggling  mo- 
tion across  the  field  of  view  in  the  microscope.  The  re- 
searches of  Madame  Luders  render  it  probable  that  the 
germs  of  fungi  develop  themselves  into  these  bodies  when 
sown  in  water  containing  animal  matter,  and  into  yeast 
in  a  saccharine  solution.  The  universal  diffusion  of  spor- 
ules  of  fungi  in  the  atmosphere  readily  accounts  for  their 
appearance  in  such  fluids,  and  Pasteur's  experiments  are 
quite  conclusive. 

The  minute  molecules  called  microzymes,  present  in  va- 
rious products  of  disease,  as  the  vaccine  vesicle,  fluid  of 
glanders,  etc. ;  the  minute  corpuscles  which  cause  the  dis- 


136  THE    MICROSCOPIST. 

ease  among  silkworms  called  "pebrine;"  etc.;  have  a 
strong  analogy  in  their  rapid  multiplication  to  the  yeast- 
cells. 

The  sporules  of  any  of  the  ordinary  moulds,  as  Penidl- 
lium,  Mucor,  or  Aspergillus,  will  develop  into  yeast-cells 
in  a  moderately  warm  solution  of  cane-suga»,  showing 
how  differently  the  same  type  of  bioplasm  may  develop 
under  different  conditions.  The  term  polymorphism  has 
been  given  to  this  phenomenon.  Very  many  species,  and 
even  genera,  so  called,  may  after  all  be  only  varieties  of 
the  same  kind  of  organism. 

In  many  morbid  conditions  of  the  skin  and  mucous 
membranes,  there  is  not  only  an  alteration  or  morbid 
growth  of  the  part,  but  a  vegetation  of  fungi.  Thrown- 
off'  scales  of  epithelium  from  the  mouth  and  fauces  exhibit 
fibres  of  leptothrix,  and  the  false  membrane  of  diphtheria, 
as  well  as  the  white  patches  of  aphtha  or  thrush,  show 
the  rnycelia  and  spores  of  fungi.  The  disease  in  silkworms 
called  muscardine  is  due  to  a  fungus,  the  Botrytis  bassiana 
(Plate  VIII,  Fig.  104),  whose  spores  enter  and  develop  in 
the  air-tubes.  The  filamentous  tufts  seen  about  dead  flies 
on  window-panes,  etc.,  arise  from  a  similar  growth  of 
Achyla.  In  certain  Chinese  or  Australian  caterpillars, 
this  sort  of  growth  becomes  so  dense  as  to  give  them  the 
appearance  of  dried  twigs.  Even  shells  and  other  hard 
tissues  may  become  penetrated  by  fungi.  The  dry  rot  in 
timber  is  a  form  of  fungus. 

The  mildew  which  attacks  the  straw  of  wheat,  etc., 
arises  from  the  Puccinia  gmminis,  whose  spores  find  their 
way  through  the  stomata  or  breathing  pores  of  the  epi- 
dermis. Rust,  and  smut,  and  bunt,  originate  in  varieties 
of  Uredo.  The  "vine  disease"  and  the  "potato  disease," 
as  they  are  called,  have  similar  origin. 

Various  methods  have  been  proposed  to  destroy  fungi 
in  growing  plants,  but  it  must  be  remembered  that  the 
function  of  these  organisms  is  chiefly  to  remove  formed 


FIG.  107: 


PLATE  IX. 


FIG.  109. 


Germ  and  Sperm-cells  in  Achyla. 


TO;-M/O  Cerevisice,  or  Yeast-Plant, 


FIG.  108. 


Development  of  fungi:  A,  mycelium;  B,  hypha;  c,  conidiophores;  D,  a  magnified  branch. 


FIG.  110. 


Various  phases  of  development  of  Palmoglaea  macrococca. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       137 

material  in  a  state  of  decay,  which  is  more  or  less  com- 
plete. The  prevalence  of  atmospheric  changes,  variations 
in  light,  heat,  moisture,  and  electricity,  etc.,  have  much 
to  do  in  predisposing  vegetable  as  well  as  animal  tissues  to 
disease  and  producing  epidemics.  The  agriculturist,  there- 
fore, as  well  as  the  physician,  must  discriminate  between 
those  diseased  conditions  which  provide  a  habitat  for 
fungi,  and  the  effects  produced  by  the  fungi  themselves. 

Impregnating  wood  with  corrosive  sublimate  or  chlo- 
ride of  zinc  has  been  used  to  prevent  dry  rot  in  wood,  and 
soaking  seeds  in  alkaline  solutions  or  sulphate  of  copper 
is  said  to  remove  smut  and  similar  fungus  spores. 

The  development  of  fungi  is  from  spores  or  conidia. 
Plate  IX,  Fig.  107,  represents  the  Torula  vegetating  by 
the  budding  of  its  spores.  These  buds  rapidly  fall  off  and 
become  independent  cells.  In  other  varieties  self-division 
gives  rise  to  the  mycelium,  a  mass  of  fibres  often  inter- 
laced so  as  to  form  a  sort  of  felt.  Some  branches  of  this 
mycelium  (hyphce)  hang  down,  while  others  rise  above  the 
surface  (conidiophores)  and  bear  conidia,  which  fall  off  and 
develop  into  new  hyphse  (Plate  IX,  Fig.  108).  In  the 
"blight"  of  the  potato  the  mycelium  is  loose,  and  the 
hyphre  ramify  in  the  intercellular  spaces  and  give  off  pro- 
jections into  the  cells  of  the  plant.  The  conidia  germinate 
by  bursting  the  sac  which  contains  them,  putting  forth 
cilia,  moving  awhile,  then  resting  and  enveloping  them- 
selves with  membrane  and  growing  into  hyphse.  In  the 
autumn,  parts  of  the  hyphse  assume  special  functions. 
One  part  develops  a  spherical  mass  called  oogonium,  while 
another  becomes  a  smaller  mass  or  antkeridium.  When 
the  first  is  ripe,  it  is  penetrated  by  the  latter,  and  the 
bioplasms  of  each  are  fused  together.  The  antheridium 
then  decays,  while  the  oogonium  grows  and  becomes  an 
oospore,  in  which  the  bioplasm  divides  and  subdivides. 
Next  season  each  segment  escapes  ciliated,  and  moves 
about  till  it  finds  a  place  to  germinate.  In  Achyla  two 


138  THE    MICROSCOPIST. 

sacs  are  formed,  one  of  which  contains  "germ-cells,"  and 
the  other  aniherozoids  or  "sperm-cells."  When  both  are 
ripe  the  sac  opens,  and  the  ciliated  antherozoids  pass  into 
the  neighboring  sac  and  fertilize  its  contents  (Plate  IX, 
Fig.  109). 

In  other  fungi  the  reproductive  cells  are  undistinguisb- 
able  from  the  rest,  and  the  coalescence  takes  place  in  a 
new  cell  formed  by  the  union  of  the  other  two. 

Mr.  Berkeley  divides  fungi  into  six  orders,  as  follows : 

1.  Hymenomycetes  or  Agaricoidece  (Mushrooms,  etc.). — 
Mycelium   flocuose,  inconspicuous,  bearing  fleshy  fruits 
which  expand  so  as  to  expose  the  hymenium  or  sporifer- 
ous  membrane  to  the  air.     Spores  generally  in  fours  on 
short  pedicles. 

2.  Gasteromycetes  or  Lycoperdoidece  (Puff  balls,  etc.). — 
Fruit  globular  or  oval,  with  convolutions  covered  by  the 
hymenium,  which  bears  the  spores  in  fours  on  distinct 
pedicles.     The  convolutions  break  up  into  a  pulverulent 
or  gelatinous  mass. 

3.  Coniomycetes  or  Uredoidece  (Smuts,  etc.). — Mycelium 
filamentous,  parasitic.     Microscopic  fructification  of  ses- 
sile or  stalked  spores  in  groups,  sometimes  septate. 

4.  Hyphomycetes  or  Botrytoidete  (Mildews,  etc.). — Micro- 
scopic.    Mycelium  filamentous,  epiphytic,  with  erect  fila- 
ments bearing  terminal,  free,  single,  simple,  or   septate 
spores. 

5.  Ascomycetes  or  HelvelloidecB  (Truffles,  etc.). — Myce- 
lium inconspicuous.     Fruit  fleshy,  leathery,  horny,  or  ge- 
latinous, lobed,  or  wrarty,  with  groups  of  elongated  sacs 
(asci  or  theece)  in  which  the  spores  (generally  eight)  are 
developed. 

6.  Physomycetes    or   Mucoroidece   (Moulds).  —  Mycelium 
(microscopic)  filamentous,  bearing  stalked  sacs  containing 
numerous  minute  sporules. 

Protophytes,  or  primitive  plants,  afford  many  forms  and 
groups  of  great  interest  to  the  microscopist  as  well  as  to 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      139 

the  biologist.  The  plan  of  the  present  work  permits  us 
only  to  indicate  a  few  particulars,  the  details  of  which 
would  form  a  volume  of  considerable  size. 

The  Algae  are  divided  into  three  orders:  I.  JRhodosper- 
mecB  or  Florida?  (Red-spored  Algce).  Marine  plants,  with 
a  leaf-like  or  filamentous  rose-red  or  purple  thallus.  II. 
Melanosporece  or  Fucoidece  (Dark-spored  Algce).  Marine. 
Thallus  leaf-like,  shrubby,  cord-like,  or  filamentous,  of 
olive-green  or  brown  color.  III.  Chlorosporece  or  Confer- 
voidece  (Green-spored  Algce).  Plants  marine  or  fresh  water, 
or  growing  on  damp  surfaces.  Thallus  filamentous,  rarely 
leaf-like,  pulverulent,  or  gelatinous.  These  have  been 
subdivided  into  families,  viz. : 

I.  Rhodospermece. — 1.  Rhodomelaceae.   2.  Laurenciaceae. 
3.  Corallinaceae.      4.  Delesseriaceae.     5.  Rhodymeniaceae. 
6.  Cryptonemiaceae.     7.  Ceramiaceae.     8.  Porphyraceae. 

II.  Melanosporece. — 1.  Fucaceae.      2.  Dictyotaceae.  3. 
Cutleriaceae.    4.  Laminariaeeae.    5.  Dictyosiphonaceae.  6. 
Punctariacese.      7.  Sporochnacese.     8.  Chordariacese.  9. 
Myrionemacese.     10.  Ectocarpacese. 

III.  Chlorosporece. — 1.  Lemaneeae.   2.  Batrachospermeee. 
3.  Choetophoraceee.      4.   Confervaceae.      5.  Zygnemace?e. 
6.  Q-Cdogoniaceae.     7.  Siphonaceae.    8.  Oscillatoriaceae.    9. 
Nostochacese.     10.  Ulvaceaa.     11.  Palmellacese.     12.  Des- 
midiaceae.     13.  Diatomaceae.     14.  Yolvocineae. 

For  fuller  information,  we  refer  to  the  Micrographic 
Dictionary  by  Griffith  and  Henfrey. 

In  the  family  of  Palmellacece  we  find  the  simplest  forms 
of  vegetation  in  the  form  of  a  powdery  layer  of  cells,  or  a 
slimy  film,  or  a  membranous  frond.  The  green  mould  on 
damp  walls  and  the  red  snow  of  alpine  regions  are  exam- 
ples. 

In  the  green  slime  on  damp  stones,  etc.,  is  found  the 
Palmoglcea  macrococca.  The  microscope  shows  it  to  con- 
sist of  cells  containing  chlorophyll,  surrounded  by  a  ge- 
latinous envelope.  These  cells  multiply  by  self-division. 


140  THE    MICROSCOPIST. 

Sometimes  a  conjugation  or  fusion  of  cells  occurs,  and  the 
product  is  a  spore  or  primordial  cell  of  a  new  generation 
(Plate  IX,  Fig.  110).  During  conjugation  oil  is  produced 
in  the  cells,  and  the  chlorophyll  disappears  or  becomes 
brown,  and  when  the  spore  vegetates,  the  oil  disappears 
and  green  granular  matter  takes  its  place.  This  is  analo- 
gous to  the  transformation  of  starch  into  oil  in  the  seeds 
of  the  higher  plants. 

Most  of  the  lower  forms  of  vegetable  life  pass  through 
what  is  called  the  motile  condition,  which  depends  on  the 
extension  of  the  bioplasm  into  thread-like  filaments,  whose 
contractions  serve  to  move  the  cell  through  the  water. 
Many  of  these  forms  were  formerly  mistaken  for  animal- 
cules, and  the  transformation  of  a  portion  of  green  chlo- 
rophyll into  the  red  form  was  represented  as  an  eye.  The 
multiplication  of  the  "still"  cells  is  by  self-division,  as  in 
Palmogl&p,,  but  after  this  has  been  repeated  about  four 
times,  the  new  cells  become  furnished  with  cilia  and  pass 
into  the  "motile"  condition,  and  their  multiplication  goes 
on  in  different  ways,  as  by  binary  or  quaternary  segmen- 
tation, or  the  formation  of  a  compound,  mulberry-like 
mass,  the  ciliated  individual  cells  of  which,  becoming  free, 
rank  as  zoospores  (Plate  X,  Fig.  111). 

The  Volvox  is  a  beautiful  example  of  the  composite 
motile  form  of  elementary  vegetation.  It  is  found  in 
fresh  water,  and  consists  of  a  hollow  pellucid  sphere, 
studded  with  green  spots,  connected  together  often  by 
green  threads.  Each  of  these  spots  has  two  cilia,  whose 
motions  produce  a  rolling  movement  of  the  entire  mass. 
Within  the  sphere  there  are  usually  from  two  to  twenty 
smaller  globes,  which  are  set  free  by  the  bursting  of  the 
original  envelope.  Sometimes  one  of  the  masses  of  endo- 
chrome  enlarges,  but  instead  of  undergoing  subdivision 
becomes  a  moving  mass  of  bioplasm,  which  cannot  be  dis- 
tinguished from  a  true  Amoeba  or  primitive  animal  cell. 

The  DesmidiacecB  are  a  family  of  minute  green  plants 


PLATE  X. 


FIG.  111. 


Various  phases  of  development  of  Protococcus  pluviulis. 


Formation  of  Zoospores  in  Phyeoseris  glgantea(Ulva  latissima). 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      141 

of  great  interest.  Generally  the  cells  are  independent, 
but  a  filament  is  sometimes  formed  by  binary  subdivision. 
Their  symmetrical  shape,  and  frequently  spinous  projec- 
tions and  peculiar  movements,  render  them  beautiful  ob- 
jects. By  conjugation  a  spore-cell  or  sporangium  is  pro- 
duced, which  in  some  species  is  spinous,  and  resembles 
certain  fossil  remains  in  flint,  which  have  been  described 
as  animalcules  under  the  name  of  Xanthidia. 

The  family  of  Diatomacece  affords  more  occupation  to 
microscopists  than  other  protophytes.  Like  the  Desmids, 
they  are  simple  cells  with  a  firm  external  coating,  but  in 
Diatoms  this  coating  is  so  penetrated  with  silex,  that  a 
cast  of  the  frustule  is  left  after  the  removal  of  the  organic 
matter.  Reference  has  already  been  made  to  the  number 
of  these  organisms  in  a  fossil  state,  as  well  as  to  their 
utility  as  tests  of  the  defining  power  of  microscopic  object- 
glasses. 

Some  species  inhabit  the  sea,  and  others  fresh  water. 
They  are  so  numerous  that  scarcely  a  ditch  or  cistern  is 
free  from  specimens,  and  they  multiply  so  rapidly  as  to 
actually  diminish  the  depth  of  channels  and  block  up 
harbors.  They  may  be  sought  for  in  the  slimy  masses 
attached  to  rocks  and  plants  in  water,  in  the  scum  of  the 
surface,  in  mud  or  sand,  in  guano,  in  the  stomachs  of 
molluscs,  etc.,  and  on  sea- weeds. 

To  separate  the  shields  or  siliceous  frustules  from  foreign 
matter,  either  fresh  or  fossil,  they  should  be  washed  sev- 
eral times  in  water,  and  the  sediment  allowed  to  subside. 
The  deposit  should  then  be  treated  in  a  test-tube  with 
hydrochloric  acid,  sometimes  aided  by  heat.  This  should 
be  repeated  as  often  as  any  effect  is  produced,  and  then 
the  sediment  should  be  boiled  in  strong  nitric  acid,  and 
washed  several  times  in  water.  They  may  be  mounted 
dry  or  in  balsam. 

The  classification  of  Diatoms  is  not  yet  perfected,  but 
Muller's  type  slides,  containing  from  one  hundred  to  five 


142  THE    MICROSCOPIST. 

hundred  characteristic  forms,  is  a  valuable  assistance. 
The  following  table,  from  the  Micrographic  Dictionary, 
gives  an  analysis  of  tribes  and  genera :  Fr.  denotes  the 
frustules  in  front  view;  v.  the  valves;  granular  striae 
means  striae  resolvable  into  dots ;  and  continuous  striae 
signify  costae  or  canaliculse. 

A.  Frustules  not  contained  in  a  Gelatinous  Mass  or  Tube. 

TRIBE  I.  STRIAT.E. — Frustules  usually  transversely  stri- 
ate,  but  neither  vittate  nor  areolate. 

t  Valves  without  a  Median  Nodule. 

COHORT  1.  EUNOTIE.E. — Fr.  arcuate,  single,  or  united 
into  a  straight  filament. 

1.  Epithemia. — Fr.  single  or  binate,  with  transverse  or 
slightly  radiant  striae,  some  continuous ;  no  terminal  nod- 
ules; aquatic  and  marine. 

2.  Eunotia. — Fr.  single  or  binate;  v.  with  slightly  ra- 
diant granular  striae  and  terminal  nodules;  aquatic. 

3.  Himantidium,. — Fr.  as  in  Eimotia,  but  united  into  a 
filament;  striae  parallel,  transverse ;  aquatic. 

COHORT  2.  MERIDE^:. — Fr.  cuneate,  single,  or  united 
into  a  curved  or  spinal  band;  v.  with  continuous  or  gran- 
ular striae. 

4.  Meridian. — Fr.  cuneate,  united  into  a  spiral  band; 
striae  continuous ;  aquatic. 

5.  Eucampia. — Fr.  united  into  an  arched  band ;  v.  punc- 
tate; marine. 

6.  Oncosphenia. — Fr.  single,  cuneate,  uncinate  at  the 
narrow  end;  striae  granular;  aquatic. 

COHORT  3.  FRAGILLARIEJE. — Fr.  quadrilateral,  single,  or 
united  into  a  filament  or  chain ;  v.  with  continuous  or 
granular  striae. 

7.  Diatom  a. — Fr.  linear  or  rectangular,  united  by  the 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       143 

angles  so  as  to  form  a  zigzag  chain;  striae  continuous; 
aquatic  and  marine. 

8.  Asterionella.—^v.  adherent  by  adjacent  angles  into 
a.  star-like   filament;   v.  inflated   at  one  or  both  ends; 
aquatic. 

9.  Fragillaria. — Fr.  linear,  united  into  a  straight,  close 
filament ;  striae  granular,  faint ;  aquatic  and  marine. 

10.  Denticula. — Fr.  linear,  simple,  or  binate,  rarely  more 
united ;  striae  continuous ;  aquatic. 

11.  Odontidium. — As  Denticula,  but  fr.  forming  a  close 
filament;  aquatic  and  marine. 

COHORT  4.  MELOSIREJE. — Fr.  cylindrical,  disk-shaped  or 
globose;  v.  punctate,  or  often  with  radiate  continuous 
or  granular  striae. 

12.  Cyclotella. — Fr.   disk-shaped,   mostly    solitary;    v. 
with  radiate  marginal  striae ;  aquatic. 

13.  Melosira. — Fr.  cylindrical  or  spherical,  united  into 
a  filament;  v.  punctate,  or  with  marginal  radiate  granu- 
lar striae ;  aquatic  and  marine. 

14.  Podosira. — Fr.  united  in  small  numbers,  cylindrical 
or  spherical,  fixed  by  a  terminal  stalk;  v.  hemispherical, 
punctate;  marine. 

15.  Mastogonia. — Fr.  single;  v.  unequal,  angular,  mam- 
miform, circular  at   base,  without   umbilical   processes ; 
angles  radiating;  fossil. 

16.  Pododiscus. — Fr.  single  or  united,  with  a  marginal 
stalk ;  v.  circular,  convex. 

17.  Pyxidicula. — Fr.  single  or  binate,  free  or  sessile; 
v.  convex  ;  aquatic  and  marine. 

18.  Stephanodiscus. — Fr.  single,  disk-shaped;   v.  circu- 
lar, equal,  punctate,  or  striate,  with  a  fringe  of  minute 
marginal  teeth ;  aquatic. 

19.  Stephanogonia. — Fr.  as  in  Mastogonia,  but  ends  of 
valves  truncate,  angular,  and  spinous;  fossil. 

20.  Hercotheca. — Fr.  single,  turgid   laterally;   v.  with 
marginal  free  setae. 


144  THE    MICROSCOPIST. 

21.  Goniothedum. — Fr.  single,  constricted  in  the  middle, 
suddenly  attenuate  and  truncate  at  the  ends  (hence  appear- 
ing angular). 

COHORT  5.  SURIRELLE.E. — Fr.  single  or  binate,  quadri- 
lateral, oval,  or  saddle-shaped,  sometimes  constricted  in 
the  middle;  v.  with  transverse  or  radiating  continuous 
or  granular  striae,  interrupted  in  the  middle,  or  with  one 
or  more  longitudinal  rows  of  puncta;  often  keeled. 

22.  Badllaria. — Fr.  prismatic,  straight,  at  first  forming 
a  filament ;  v.  with  a  median  longitudinal  row  of  puncta ; 
marine. 

23.  Campylodiscus. — Fr.    single,   free,   disk-shaped;   v. 
curved  or  twisted  (saddle-shaped);  aquatic  and  marine. 

24.  Doryphora. — Fr.  single,  stalked ;   v.  lanceolate  or 
elliptical,  with  transverse  granular  striae. 

25.  Podocystis. — Fr.  attached,  sessile;  v.  with  a  median 
line,  transverse   continuous,  and   intermediate   granular 
striae. 

26.  Nitzschia. — Fr.  free,  single,  compressed,  usually  elon- 
gate, straight,  curved,  or   sigmoid,  with    a   not-median 
keel,  and   one   or  more   longitudinal   rows   of    puncta; 
aquatic  and  marine. 

27.  Sphinctocystis(Cymatopleura). — Fr. free, single, linear, 
with  undulate  margins ;  v.  oblong  or  elliptical,  sometimes 
constricted  in  the  middle;  aquatic. 

28.  Surirella. — Fr.  free,  single,  ovate,  elliptical,  oblong, 
cuneate,  or  broadly  linear ;  v.  with  a  longitudinal  median 
line  or  clear  space,  margins  winged,  and  with  transverse 
or  slightly  radiating  continuous  stride ;  aquatic  and  marine. 

29.  Synedra. — Fr.  prismatic,  rectangular,  or  curved ;  at 
first  attached  to  a  gelatinous-lobed  cushion,  often  becom- 
ing free;  v.  linear  or  lanceolate,  usually  with  a  median 
pseudo-nodule  and  longitudinal  line  ;  aquatic  and  marine. 

30.  Tryblionella. — Fr.  free,  linear,  or  elliptical ;  v.  plane, 
with  a  median  line,  transverse  striae,  and  submarginal  or 
obsolete  alse ;  aquatic  and  marine. 


THE    MICROSCOPE    IN   HISTOLOGY    AND    BOTANY.      145 

• 

31.  Raphoneis.—Doryphora  without  a  stalk. 

COHORT  6.  AMPHIPLEURE^E. — Fr.  free,  single,  straight, 
or  slightly  sigrnoid ;  v.  lanceolate,  or  linear-lanceolate, 
with  a  median  longitudinal  line. 

32.  Amphipleura. — Characters  as  above. 


ft  Valves  with  a  Median  Nodule. 

COHORT  7.  COCCONEID^:. — Fr.  straight  or  bent,  attached: 
by  the  end  or  side;  v.  elliptical,  equilateral. 

33.  Cocconeis. — Fr.  single,  compressed,  adnate;  v.  ellip- 
tical, one  of  them  with  a  median  line. 

COHORT  8.  ACHNANTHE.E. — Fr.  compressed,  single,  or 
rarely  united  into  a  straight  filament,  curved,  attached 
by  a  stalk  at  one  angle;  uppermost  v.  with  a  longitudinal 
median  line,  lower  v.  the  same,  and  a  stauros  or  transverse 
line;  marine. 

35.  Achnanthidium. — Fr.  those  of  Achnanthes,  but  free ; 
aquatic. 

36.  Cymbosim. — Fr.  as  Achnanthes,  solitary  or  binate, 
stipitate,  and  attached  end  to  end ;  marine. 

COHORT  9.  CYMBELLE^E. — Fr.  straight  or  curved,  free  or 
stalked  at  the  end ;  v.  inequilateral,  not  sigmoid. 

37.  Cymbella. — Fr.  free,  solitary;  v.  navicular,  with  a 
subcentral  and  two  terminal  nodules,  and  a  submedian 
longitudinal  line ;  aquatic. 

38.  Cocconema. — Fr.  as  Cymbella,  but  stalked;  aquatic. 
COHORT  10.  GOMPHONEME.E. — Fr.  wedge-shaped,  straight, 

free,  or  stalked ;  v.  equilateral. 

39.  Gomphonema. — Fr.  single  or  binate,  wedge-shaped, 
attached  by  their  ends  to  a  stalk;  v.  with  a  median  line, 
and  a  median  and  terminal  nodules;  aquatic. 

40.  Sphenella. — Fr.  free,  solitary,  wedge-shaped,  invo- 
lute; aquatic. 

10 


146  THE    MICROSCOPIST. 

41.  Sphenosira. — Fr.  united  into  a  straight  filament;  v. 
wedge-shaped,  at  one  end  rounded,  suddenly  contracted 
and  produced;  aquatic. 

COHORT  11.  NAVICULE^;.— Fr.  free,  straight;  v.  equilat- 
eral, or  sometimes  sigmoid. 

42.  Navicula. — Fr.  single,  free,  straight ;  v.  oblong,  lan- 
ceolate, or  elliptical,  with  a  median  line,  a  central  and  two 
terminal  nodules,  and  transversely  or  slightly  radiant  lines 
resolvable  into  dots ;  aquatic,  marine,  and  fossil. 

43.  Gyrosigma  (Pleurosigma). — Fr.  as  Navicula,  but  v. 
sigmoid ;  aquatic  and  marine. 

44.  Pinnularia. — Fr.  as  Navicula,  but  transverse  lines 
continuous ;  aquatic  and  marine. 

45.  Stauroneis. — Fr.  as  Navicula,  but  the  median  line 
replaced  by  a  stauros;  aquatic  and  marine. 

46.  Diadesmis. — Fr.  as  Navicula,  united  into  a  straight 
filament;  aquatic. 

47.  Amphiprora. — Fr.  free,  solitary,  or  in  pairs,  con- 
stricted in  the  middle;  v.  with  a  median  keel,  and  a 
median  and  terminal  nodules,  often  twisted ;  marine. 

48.  Amphora. — Fr.  plano-convex,  elliptical,  oval  or  ob- 
long, solitary,  free  or  adnate,  with  a  marginal  line,  and  a 
nodule  or  stauros  on  the  flat  side ;  aquatic  and  marine. 


TRIBE  II.  VITIATE.  —  Fr.  with  vittee. 

t  Valves  without  a  Median  Nodule. 

COHORT  12.  LICMOPHORE.E. — Fr.  cuneate;  vittfe  arched. 

49.  Licmophora.- — Fr.  cuneate,  rounded  at  the  broad 
end,  radiating  from  a  branched  stalk;  vittse  curved  (by 
inflection  of  upper  margins  of  valves) ;  marine. 

50.  Podosphenia.—Fr.  as  Licmophora,  but  single  or  in 
pairs,  sessile  on  a  thick  but  little  branched  pedicle;  ma- 
rine. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      147 

51.  Rhipidophora. — Fr.  as  Licmophora,  single  or  in  pairs, 
on  a  branched  stipes ;  marine. 

52.  Climacosphenia. — Fr.  cuneate,  rounded  at  broad  end, 
divided  into  loculi  by  transverse  septse  or  vittse ;  marine. 

COHORT  13.  STRIATELLE^;. — Fr.  tabular  or  filamentous; 
vittee  straight  (not  arched). 

53.  Striatella. — Fr.  compound,  stalked   at   one   angle; 
vittse  longitudinal  and  continuous  ;  v.  elliptic-lanceolate, 
not  striated  ;  marine. 

54.  Rhabdonema. — Fr.  as   Striatella,  but    vittse    inter- 
rupted ;  v.  with  transverse  granular  strise ;  marine. 

55.  Tetracydus. — Fr.  compound,  filamentous ;  vittee  al- 
ternate, interrupted ;  v.  inflated  at  the  middle ;  striae  trans- 
verse, continuous  ;  aquatic. 

56.  Tabellaria. — Fr.  united  into  a  filament,  subsequently 
breaking  up  into  a  zigzag  chain  ;  vittoe  interrupted,  alter- 
nate ;  v.  inflated  at  middle  and  ends ;  aquatic. 

57.  Pleurodesmium. — Fr.  tabular,  united  into  a  filament, 
and  with  a  transverse  median  hyaline  band ;  marine. 

58.  Hyalosira. — Fr.  tabular,  fixed  by  a  stalk   at  one 
angle  ;  vittse  alternate,  interrupted,  bifurcate  at  the  end  ; 
marine. . 

59.  Anaulus. — Fr.  rectangular,  single,  compressed,  with 
lateral  inflections,  giving  the  valves  a  ladder-like  appear- 
ance ;  marine. 

60.  Biblarium. — Fr.  as  Tetracydus,  but  single  ;  fossil. 

61.  Terpsinoe. — Fr.  tabular,  obsoletely   stalked,  subse- 
quently connected  by  isthmi ;  vittse  transverse,  short,  in- 
terrupted, and  capitate  ;  aquatic  and  marine. 

62.  Stylobiblium. — Fr.  compound ;  v.  circular,  sculptured 
with  continuous  strise  ;  fossil. 


ft  With  a  Median  apparent  (pseudo)  Nodule. 
63.  Grrammatophora. — Fr.  at  first   adnate,  afterwards 


148  THE    MICROSCOPIST. 

forming  a  zigzag  chain ;  vittse  two,  longitudinal,  inter- 
rupted, and  more  or  less  figured  ;  marine. 

TRIBE  III.  AREOLAM. — Valves  circular,  with  cell-like 
(areolar)  markings,  visible  by  ordinary  illumination. 

SUB-TRIBE  1.  DISCIFORMES. — Valves  alike,  without  ap- 
pendages or  processes. 

COHORT  14.  COSCINODISCE.E. — Valves  circular. 

64.  Actinocydus. — Fr.   solitary;    v.   circular,  undulate, 
the  raised  portions  like  rays  or  bands  radiating  from  the 
centre,  which  is  free  from  markings  ;  marine  and  fossil. 

65.  Actinoptychm. — Fr.  as  Actinocydus,  but   radiating 
internal  septae,  as  well  as  rays. 

66.  Coscinodiscus . — Fr.  single ;   v.  circular,  areolar  all 
over ;  marine  and  fossil. 

67.  Aracknoidiscus. — Fr.  single ;  v.  circular,  not  undu- 
late, with  concentric  and  radiating  lines,  and  intermediate 
areola  absent  from  the  centre  (pseudo-nodule);   marine 
and  fossil. 

68.  Asterolampra. — Fr.  single ;  v.  circular,  finely  areolar, 
except  in  the  centre  and  at  equidistant  clear  marginal  rays 
radiating  from  the  centre,  which  is  traversed  by  radiating 
dark  lines  (septa),  alternating  with  the  marginal  rays  ; 
fossil. 

69.  Aster  omphalos. — As  Asterolampra,  but  two  of  the 
central  dark  lines  parallel,  and  the  corresponding  mar- 
ginal ray  obliterated ;  fossil. 

70.  Halionyx. — Fr.  single ;  v.  circular,  without  septa, 
with  rays  not  reaching  the  centre,  and  with  intermediate 
shorter  rays ;  between  the  rays  transverse  areolar  lines ; 
fossil. 

71.  Odontodiscus. — Fr.    single,   lenticular ;    v.   covered 
with  puncta  (areolee),  arranged  in  radiating  rows  on  ex- 
centrically  curved  lines,  and  with  erect  marginal  teeth  ; 
fossil. 

72.  Omphalopelta. — As  Actinoptychus,  but  upper  part  of 
margin  of  valves  with  a  few  erect  spines  ;  fossil. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       149 

73.  Symbolophora. — Fr.  single,  disk-shaped ;  v.  with  in- 
complete septa  radiating  from  the  solid  angular  umbili- 
cus, and  intermediate  bundles  of  radiating  lines ;  marine 
and  fossil. 

74.  Systephania. — Fr.  single ;  v.  circular,  areolar,  with- 
out rays  or  septa,  with  a  crown  of  spines  or  an  erect 
membrane  on  the  outer  surface  of  each  valve ;  fossil. 

COHORT  15.  ANGULIFERA. — Valves  angular. 

75.  Amphitetras. — Fr.  at  first  united,  afterwards  sepa- 
rating into  a  zigzag  chain,  rectangular;  v.  rectangular, 
the  angles  often  produced  ;  marine. 

76.  Amphipentras. — Fr.  solitary ;  v.  pentangular ;  fossil. 

77.  Lithodesmium. — Fr.  united  into  a  straight  filament ; 
v.  triangular,  one  side  plane,  the  others  undulate ;  marine. 


TRIBE  IY.  APPENDICULAT^E. — Valves  with  processes  or 
appendages,  or  with  the  angles  produced  or  inflated. 
COHORT  16.  EUPODISCEJE. — Fr.  disk-shaped  ;  v.  circular. 

78.  Eapodiscus. — Fr.  single,  disk-shaped ;   v.  circular, 
with  tubular  or  horn-like  processes  on  the  surface ;  aquatic 
and  marine. 

79.  Auliscus. — As  Eupodiscus^but  processes  obtuse  and 
more  solid ;  fossil. 

80.  Insilella. — Fr.  single,  fusiform ;   v.  equal,  with   a 
median  turgid  ring  between  them  ;  marine. 

COHORT  17.  BIDDULPHIE^E. — Fr.  flattened;  v.  elliptical 
or  suborbicular. 

81.  Biddidphia. — Fr.  rectangular,  more  or  less  united 
into  a  continuous  or  zigzag  filament ;  the  angles  inflated 
or  produced  into  horns  ;  v.  convex,  centre  usually  spinous  ; 
marine. 

82.  Isthmia. — Fr.  rhomboidal  or  trapezoidal,  cohering 
by  one  angle ;  angles  produced ;  marine. 

83.  Chcetoceros. — Fr.  compressed ;  v.  equal,  with  a  long 
spine  or  filament  on  each  side  ;  marine. 


150  THE    MICROSCOPIST. 

84.  Rhizoselenia. — Fr.  elongate,  subcylindrical,  marked 
with  transverse  or  spiral  lines,  ends  oblique  or  conical, 
and  with  one  or  more  terminal  bristles ;  marine. 

85.  Hemiaulus. — Fr.   single,   compressed,  rectangular; 
angles  produced  into  tubular  direct  processes,  those  on 
one  valve  longer  than  on  the  other  ;  fossil. 

86.  Syringidium. — Fr.  single,  terete,  acuminate  at  one 
end,  two-horned  at  the  other  ;  marine. 

87.  Periptera.—Fr.  single,  compressed  ;  v.  unequal,  one 
simply  turgid,  the  other  with  marginal  wings  or  spines ; 
fossil. 

88.  Didadia. — Fr.  single;  v.  unequal,  one  turgid  and 
simple,  the  other  two-horned  ;  fossil. 

COHORT  18.  ANGULAT^E. — Valves  angular. 

89.  Triceratium. — Fr.  free ;   v.  triangular,  each   angle 
with  a  minute  tooth  or  horn  ;  marine. 

90.  Syndendrium. — Fr.  single,  subquadrangular ;  v.  un- 
equal, slightly  turgid,  one  smooth,  the  other  with  numer- 
ous median  spines,  or  little  horns  branched  at  the  ends. 


B.  Frustules  enveloped  in  a  mass  of  Gelatin,  or  contained  in 
Gelatinous  Tubes,  forming  a  Frond. 

91.  Mastogloia. — Frond  mammilate ;  fr.Jike  Navicula, 
but  hoops  with  loculi ;  aquatic  and  marine. 

92.  Dickieia: — Frond    leaf-like ;    fr.  like   Namcula    or 
Stamoneis  ;  marine. 

93.  Berkeley^. — Frond  rounded  at  base,  filamentous  at 
circumference  ;  fr.  navicular ;  marine. 

94.  Homoeocladia. — Frond  sparingly  divided,  filiform ; 
fr.  like  Nitzschia  ;  marine. 

95.  Colletonema.  —  Frond    filamentous,   filaments    not 
branched ;  fr.  like  Namcula  or  Gyrosigma  ;  aquatic. 

96.  Schizonema. — Frond  filamentous,  branched ;  fr.  like 
Namcula;  marine. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       151 

97.  Encyonema. — Frond  filamentous,  but  little  branched  ; 
f'r.  like  Cymbella  ;  aquatic. 

98.  Syncydia. — Fr.  those  of  Cymbella,  united  in  circular 
bands,  immersed  in  an  amorphous  gelatinous  frond  ;  ma- 
rine. 

99.  Frustulia. — Fr.  as  Navicula,  irregularly  scattered 
through  an  amorphous  gelatinous  mass  ;  aquatic. 

100.  Micromega. — Fr.  as  Navicula,  arranged  in  rows  in 
gelatinous  tubes,  or  surrounded  by  fibres,  these  being  in- 
closed in  a  filiform  branched  frond  ;  marine. 

The  family  of  Nostochince  is  allied  to  the  Palmellacece. 
It  consists  of  beaded  filaments  suspended  in  a  gelatinous 
frond.  The  gelatinous  masses  of  Nostoc  often  appear  quite 
suddenly  in  damp  places,  and  have  been  called  "fallen 
stars."  They  attracted  the  notice  of  the  alchemists,  and 
enter  into  many  of  their  recipes  for  the  transmutation  of 
metals.  What  have  been  termed  showers  of  flesh  or  of 
blood,  originated  in  all  probability  in  the  rapid  develop- 
ment of  similar  masses.  Many  botanists  regard  them  as 
the  "  gonidia  "  of  Collema  and  other  lichens. 

The  Oscillatoria,  so  called  from  the  singular  oscillatory 
motion  of  their  filaments,  consist  also  of  cells  which  mul- 
tiply in  a  longitudinal  direction  by  self-division.  The 
Ulvacece,  to  which  the  grass-green  sea-weeds  belong,  in- 
crease in  breadth  as  well  as  length  by  the  subdivision  of 
cells,  so  as  to  produce  a  leaf-like  expansion  (Plate  X,  Fig. 
112).  An  illustration  of  the  simpler  forms  of  reproduction 
in  Protophytes  is  seen  in  Zygnema,&Q  called  from  the  sin- 
gular manner  in  which  the  filaments  are  yoked  together 
in  pairs.  In  an  early  stage  of  growth,  while  multiplica- 
tion of  cells  proceeds  by  subdivision,  the  endochrome  is 
generally  diffused,  but  about  the  time  of  conjugation  it 
arranges  itself  usually  into  a  spiral.  Adjacent  cells  put 
forth  protuberances,  which  unite  and  form  a  free  passage 
between  them,  and  the  endochrome  of  one  cell  passes  over 


152  THE    MICROSCOPIST. 

into  the  other  and  forms  the  spore.  In  Sphoeroplea  the 
endochrome  of  the  "  oospore  "  breaks  up  into  segments, 
which  escape  as  "  microgonidia."  Each  of  these  have 
two  vibratile  filaments,  which  elongate  so  as  to  become 
fusiform,  and  at  the  same  time  change  from  red  to  green. 
Losing  their  motile  power  they  become  filaments,  in  which 
the  endochrome,  by  the  multiplication  of  vacuoles,  be- 
comes frothy.  After  a  time  the  particles  of  endochrome 
assume1  a  globular  or  ovoid  shape,  and  openings  occur  in 
the  cell- wall.  In  other  filaments  the  endochrome  is  con- 
verted into  antherozoids,  each  of  which  is  furnished  with 
two  filaments,  by  means  of  which  they  swim  about  and 
enter  the  openings  of  the  spore-cells,  in  which  they  seem 
to  dissolve  away.  The  contents  of  the  spore-cell  then 
becomes  invested  with  a  membranous  envelope ;  the  color 
changes  from  green  to  red  ;  a  second  investment  is  formed 
within  the  first,  which  extends  itself  into  stellate  projec- 
tions. When  set  free  the  mass  is  a  true  oospore,  and 
ready  to  repeat  the  process  above  described.  In  GEdogo- 
nium  the  antherozoids  are  developed  in  a  body  called  an 
"  androspore,"  which  is  set  free  from  a  germ-cell,  and 
which  being  furnished  with  cilia  resembles  an  ordinary 
zoospore.  This  androspore  attaches  itself  to  the  outer 
surface  of  a  germ-cell,  a  sort  of  lid  drops  from  its  free 
extremity,  which  sets  free  its  contained  antherozoids. 
These  enter  an  aperture  formed  in  the  cell- wall  of  the 
oospore,  and  fertilize  the  contained  mass  by  blending 
with  it. 

Examination  of  the  Higher  Cryptogamia. — It  would  en- 
large this  volume  far  beyond  its  proposed  limits  to  refer 
to  the  particular  instances  of  form  or  function  which  the 
microscope  reveals  to  the  systematic  botanist  or  physiolo- 
gist, nor  is  this  necessary,  since  well-written  treatises  on 
structural  botany  are  quite  available.  We  content  our- 
selves, therefore,  in  the  remainder  of  this  chapter,  with 
pointing  out  the  methods  of  examination  by  which  the 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       153 

views  of  other  observers  may  be  verified,  or  additions 
made  to  our  knowledge  of  vegetable  life. 

The  lower  forms  of  algae  and  fungi,  to  which  we  have 
already  referred,  need  scarcely  any  preparation,  save  the 
disentanglement  of  twisted  threads  under  the  simple  mi- 
croscope, or  a  gentle  teasing  with  needles,  or  rinsing  with 
water.  The  solution  of  iodine,  and  of  iodine  and  sulphuric 
acid,  will  suffice  to  exhibit  the  nature  of  the  cell-wall  and 
cell-contents.  In  more  highly  developed  plants  it  will  be 
necessary  to  take  thin  sections  from  different  parts,  a'nd 
in  different  but  definite  directions.  These  sections  may 
be  made  by  hand,  or  between  pieces  of  pith  or  cork  by 
means  of  a  section  cutter.  In  some  instances  some  of  the 
methods  of  staining  will  also  be  useful.  Dr.  Hunt,  of 
Philadelphia,  has  proposed  a  plan  of  staining  which  is 
well  adapted  to  all  vegetable  tissues.  He  first  soaks  the 
part  or  section  in  strong  alcohol  to  dissolve  the  chloro- 
phyll, then  bleaches  it  in  a  solution  of  chlorinated  soda. 
It  is  then  placed  in  a  solution  of  alum,  and  afterwards  in 
one  of  extract  of  logwood.  By  transferring  it  to  weak 
alcohol  and  afterwards  to  stronger,  it  is  deprived  of  its 
water,  and  after  being  made  transparent  with  oil  of  cloves, 
it  is  ready  for  mounting  in  balsam  or  dammar  varnish. 
Care  must  be  taken  to  wash  it  well  after  each  of  the 
preliminary  steps  before  staining. 

In  the  higher  algse,  the  layers  of  cells  assume  various 
sizes  and  shapes,  and  the  nature  of  their  fructification  is 
of  great  interest.  Sections  may  be  made  of  the  "  recep- 
tacles "  at  the  extremities  of  the  fronds,  which  contain 
filaments,  whose  contents  become  antherozoids.  The  pear- 
shaped  sporangia  in  the  receptacles  subdivide  into  clusters 
of  eight  cells,  called  octospores,  which  are  liberated  from 
their  envelopes  before  fertilization. 

The  red  sea-\veeds,  or  Rhodospermece,  afford  many  beau- 
tiful forms  for  the  microscope.  The  "  tetraspores "  are 
imbedded  in  the  fronds. 


THE    MICROSCOPIST. 

In  lichens,  the  apothecia  form  projections  from  the  thal- 
lus,  or  general  expansion  produced  by  cell-division.  A 
vertical  section  shows  them  to  contain  asci  or  spore-cases 
amid  straight  filaments,  or  elongated  cells  called  para- 
physes. 

The  fronds  of  Hepaticce  or  liverworts  bear  stalks  with 
shield-like  disks,  which  carry  antheridia,  and  others  with 
radiating  bodies  bearing  archegonia,  which  afterwards 
give  place  to  the  sporangia  or  spore-cases.  The  spores 
are  associated  with  elaters,  or  elastic  spiral  fibres,  which 
suddenly  extend  themselves  and  disperse  the  spores. 

The  Characece  are  often  inc rusted  with  carbonate  of 
lime,  which  may  be  removed  with  dilute  sulphuric  acid. 
The  motion  of  the  bioplasm  in  the  cells  of  the  stem  is 
often  well  seen.  The  cells  in  which  the  spiral  filaments 
or  antheridia  are  developed,  are  strung  together  like  a 
row  of  pearls.  The  position  and  construction  of  the  spores 
also  should  be  examined,  as  well  as  the  mode  of  growth 
in  the  plant  by  division  of  the  terminal  cell  (Plate  XI, 
Fig.  113). 

Stems  of  mosses  and  liverworts  should  be  examined  by 
means  of  transverse  and  longitudinal  sections.  Similar 
sections  through  the  half-ripe  fruit  of  a  moss  will  show 
the  construction  of  the  fruit,  the  peristome,  the  calyptra, 
etc.  The  ripe  spores  may  be  variously  examined  dry,  in 
water,  in  oil  of  lemons,  and  in  strong  sulphuric  acid.  The 
capsules  or  urns  of  mosses  are  not  now  regarded  as  their 
fructification,  but  its  product. 

The  true  antheridia  and  pistillidia  are  found  among  the 
bases  of  the  leaves,  close  to  the  axis.  The  fertilized  "  em- 
bryo-cell "  becomes  gradually  developed  by  cell-division 
into  a  conical  body  or  spore-capsule,  elevated  on  a  stalk. 
The  peristome,  or  toothed  fringe,  seen  around  the  mouth 
of  the  urn  when  the  calyptra  or  hood,  and  operculum  or 
lid,  are  removed,  furnishes  a  beautiful  object  for  the  bi- 
nocular microscope. 


PLATE  XI. 

FIG. 113. 


Antheridia  of  Chara  fragilix:—  A,  antheridium  or  "globule"  developed  at  the  base  of  pistillidinm  or 
"nucule;"  B,  nucule  enlarged,  globule  laid  open  by  the  separation  of  its  vaivos;  c,  one  of  the  valves, 


with  its  group  of  antheridial  filaments,  each  composed  of  a  linear  series  of  cells,  within  every  ono  of 
which  an  antherozoid  is  formed  ;  in  D,  K,  and  F,  the  successive  stages  of  this  formation  are  seen  ;  and  at 
G  is  shown  the  escape  of  the  mature  autherozoids,  11.  (From  Carpenter.) 


Development  of  Prothalium  of  Plerix  serruJnta: — A,  spore  set  free  from  the  theca;  B,  spore  beginning 
to  germinate,  putting  forth  the  tubular  prolongation  n,  from  the  principal  cell  b;  c,  fi-st  formed  linear 
series  of  cells ;  D,  prothaliinm  taking  the  form  of  a  leaf-like  expansion ;  a  first  and  b  second  radical 
fibre ;  c,  </,  the  two  lobps.  and  e  the  indentation  between  them  ;  /,  /',  first-formed  part  of  the  prothallium ; 
g,  external  coat  of  the  original  spore  ;  A,  A,  aiitheridia.  (From  Carpenter.) 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       155 

The  Sphagnum,  or  bog-moss,  has  large  and  elongated 
leaf-cells,  with  loosely-coiled  spiral  fibres,  and  their  mem- 
branous walls  have  large  apertures.  Their  spores  are  of 
two  kinds,  and  when  germinating  in  water,  produce  a  long 
filament  with  root-fibres  at  the  lower  end  and  a  nodule 
at  the  upper,  from  which  the  young  plant  is  formed.  If 
grown  on  wet  peat,  instead  of  a  filament  there  is  evolved 
a  lobed  foliaceous  protkattitttn,  resembling  the  frond  of 
liverworts. 

In  ferns  the  structure  approximates  to  true  flowering 
plants,  while  the  reproductive  organs  are  those  of  crypto- 
gamia.  Thin  sections  of  the  stem,  cut  obliquely,  show 
the  scalariform  or  ladder-like  vessels.  The  fructification 
is  usually  found  on  the  under  side  of  the  frond  in  isolated 
spots  called  sori.  Each  of  these  contains  a  number  of  cap- 
sules or  thecce,  and  each  capsule  is  surrounded  by  an  an- 
nidus  or  ring,  whose  elasticity  opens  the  capsule  when 
ripe  and  permits  the  spores  to  escape.  The  spores  are 
somewhat  angular,  and  when  vegetating  give  rise  to  a 
leaf-like  expansion  called  a  prothallium.  In  this  the  an- 
theridia  and  archegonia,  which  represent  the  true  flower 
of  higher  plants,  are  developed.  The  ciliated  anthero- 
zoids  from  the  antheridia  penetrate  the  cavity  of  the 
archegonium  and  fertilize  the  u  germ-cell,"  which  subdi- 
vides and  becomes  a  young  fern,  while  the  prothallium, 
having  discharged  the  functions  of  a  nurse,  withers  away 
(Plate  XI,  Fig.  114).  The  group  of  JSquisetacece  or  horse- 
tails is  interesting  from  the  siliceous  skeletons  of  the  epi- 
dermis, already  referred  to,  page  131,  as  well  as  for  the 
elastic  filaments  attached  to  their  spores. 

EXAMINATION  OF  HIGHER  PLANTS. 

The  elementary  tissues  described  in  the  beginning  of 
this  chapter  are  chiefly  characteristic  of  phanerogamic 
plants,  yet  some  additional  particulars  remain  to  be  no- 


156  THE    MICROSCOPIST. 

ticed  in  connection  with,  the  axis  or  stem,  the  leaves, 
flowers,  and  fruit. 

1.  The  Stem. — The  arrangement  of  fibre-vascular  bun- 
dles, i.  e..  woody  fibres  and  ducts,  differs  widely  in  the 
two  botanical  divisions  of  Monocotyledons  and  Dicotyle- 
dons. In  the  first  the  growth  is  endogenous,  and  a  section 
exhibits  the  bundles  of  fibres  and  ducts  disposed  without 
regularity  in  the  mass  of  cellular  tissue  which  forms  the 
basis  of  the  fabric.  In  the  second,  or  exogenous  stems, 
the  fibro-vascular  bundles  are  wedge-shaped,  and  inter- 
posed between  the  bark  and  the  pith,  being  kept  apart  by 
plates  of  cellular  tissue,  called  medullary  rays,  proceeding 
from  the  pith. 

The  course  of  the  vascular  bundles  in  monocotyledons 
should  be  carefully  followed,  either  by  maceration  or 
minute  dissection.  In  the  dicotyledonous  stem,  sections 
must  be  made  in  three  directions,  transversely,  longitu- 
dinally across  the  diameter,  and  at  a  tangent  from  the 
bundles  of  fibres.  The  section-cutter,  described  page  63, 
will  be  serviceable,  although  a  sharp  razor  or  scalpel  may 
serve.  The  size,  form,  and  contents  of  the  pith-cells 
should  be  noticed,  and  their  transition  to  wood-cells. 
The  arrangement  of  the  medullary  rays,  of  the  wood-cells, 
and  of  the  ducts  must  also  be  observed,  and  in  the  Coni- 
ferae  the  position  of  the  pits.  The  cambium  layer,  between 
the  bark  and  wood,  may  have  its  cells  rendered  more 
transparent  by  weak  alkalies,  and  their  contents  tested 
with  iodine  solution.  The  course  and  construction  of 
laticiferous  vessels  in  the  bark,  when  present,  and  of  the 
cork-cells  of  the  tuberous  layer,  may  be  noted. 

Fossil  woods  may  be  cut  with  a  watch-spring  saw,  and 
ground  on  a  hone  like  bone  or  teeth.  Sometimes  it  is 
best  to  break  off  small  lamella  by  careful  strokes  with  a 
steel  hammer.  It  is  sometimes  useful  to  digest  fossil 
wood  in  a  solution  of  carbonate  of  soda  for  several  days 
before  cutting. 


THE    MICROSCOPE    IN   HISTOLOGY    AND    BOTANY.      157 

2.  Leaves. — These  should  be  examined  by  thin  longitu- 
dinal and  transverse  sections.    The  epidermis  of  both  sides 
should  be  detached,  and  the  position  and  arrangement  of 
the  stomata  observed  (Plate  VII,  Fig.  100).     The  hairs 
of  the  epidermis,  the  arrangement  of  the  parenchyma,  and 
the  distribution  of  the  vascular  bundles  in  the  form  of 
nerves,  are  also  of  importance. 

3.  Flowers. — For  ascertaining  the  number  and  position 
of  the  parts  of  the  flower,  transverse  sections  at  different 
heights  through  an  unopened  bud  may  be  taken,  together 
with  a  longitudinal  section  exactly  through  the  middle. 
The  general  structure  of  sepals  and  petals  corresponds  with 
that  of  leaves,  but  there  are  some  peculiarities.     Thus  the 
cells  of  the  petal  of  the  geranium  exhibit  when  deprived 
of  epidermis,  dried  and  mounted  in  balsam,  a  peculiar 
mammillated  appearance  with  radiating  hairs  (Plate  VIII, 
Fig.  102).     Anthers  and  pollen  grains  are  also  interesting 
microscopic  objects.     The  protrusion  of  the  inner  mem- 
brane through  the  exterior  pores  in  pollen  may  be  stimu- 
lated by  moistening  with  water,  dilute  acid,  etc.     The 
penetration  of  the  pollen  tubes  through  the  tissue  of  the 
style  may  be  traced  by  sections  or  careful  dissection.     The 
heartsease,  viola  tricolor,  and  the  black  and  red  currant, 
ribes  nigrum  and  rubrum,  have  been  recommended  for  this 
purpose. 

4.  Seeds. — The   reticulations  or  markings  on  various 
kinds  of  seeds  render  them  frequent  objects  for  observa- 
tion with  the  binocular  microscope.     Adulterations  may 
also  be  detected  in  this  way,  as  well  as  imperfect  seeds  in 
any  sample,  a  subject  of  much  importance  to  the  practical 
farmer. 


153  THE    MICROSCOPIST. 

CHAPTER    XL 

THE   MICROSCOPE   IN   ZOOLOGY. 

WE  have  already  seen  that  both  animal  and  vegetable 
structures  originate  in  a  jelly-like  mass  or  cell,  and  that 
in  the  simple  forms  it  is  difficult,  if  not  impossible,  to 
determine  whether  the  object  is  an  animal  or  a  vegetable. 
The  mode  of  alimentation,  and  not  structure,  is  our  only 
guide  in  the  discrimination  of  the  Protozoa  or  elementary 
animal  forms  from  Protophytes  or  simple  vegetables. 

It  has  been  proposed  by  Professor  Heeckel  to  revive  the 
idea  of  a  kingdom  of  nature  intermediate  between  plants 
and  animals,  but  it  does  not  appear  that  any  gain  to  sci- 
ence would  result  from  such  an  arrangement. 

I.  MONERA. — The  simplest  types  of  Protozoa  are  mere 
particles  of  living  jelly  (Plate  XII,  Fig.  115),  yet  they 
possess  the  power  of  contraction  and  extension,  and  of 
absorbing  alimentary  material  into  their  own  substance 
for  its  nutrition.     The  Bathybius^  from  the  "globigerina 
mud,"  referred  to  on  page  9d,  seems  to  have  been  an  in- 
definite expansion  of  such  protoplasm  or  bioplasm. 

II.  RHIZOPODS. — This  term  (meaning  root-footed)  is  ap- 
plied to  such  masses  of  sareode  or  bioplasm  as  extend  long 
processes,  called  pseudopodia,  as  prehensile  or  locomotive 
organs  (Plate  XII,  Fig.  116).     The  Rhizopods  are  either 
indefinitely  organized  jelly,  like  Monera,  or  attain  a  cov- 
ering or  envelope  of  membrane  called  ectosarc,  while  the 
thin  contents  are  termed  endosarc.     The  first  order  of 
Rhizopods,  Reticularia,  consist  of  indefinite  extensions  of 
freely  branching  and  mutually  coalescing  bioplasm.     The 
second  order,  Radidaria,  have  rod-like  radiating  exten- 
sions of  the  ectosarc,  which  do  not  coalesce.     The  order 
Lobosa  are  lobose  extensions  of  the  body  itself,  as  in  the 


THE    MICROSCOPE    IN    ZOOLOGY.  159 

Amoeba  prince ps  already  described.  Some  of  this  latter 
order, as  Arcella  and  Difflugia^&re  testaceous.  In  Arcella 
the  test  is  a  horny  membrane,  analogous  to  the  chitine 
which  hardens  the  integuments  of  insects.  In  Difflugia 
the  test  is  made  up  of  minute  particles  of  gravel,  shell, 
etc.,  cemented  together.  From  the  opening  the  amosboid 
body  puts  forth  its  pseudopodia  (Plate  XII,  Fig.  117). 
Connected  with  Rhizopods  are  three  remarkable  series  of 
forms,  generally  marine,  and  distinguished  by  skeletons 
of  greater  or  less  density,  which  afford  many  objects  of 
interest  to  the  microscopist.  These  are  the  Foraminifera^ 
the  Polycystina,  and  the  Sponges  or  Porifera.  The  shells 
of  the  Foraminifera  are  calcareous,  and  those  of  Polycys- 
tina siliceous ;  both  are  perforated  with  numerous  aper- 
tures, which  in  Polycystina  are  often  large.  We  have 
previously  referred  to  these  forms  as  occurring  in  a  fossil 
state. 

Some  Foraminifera  have  porcellanous,  and  others  vitre- 
ous or  hyaline  shells,  usually  many-chambered,  and  of  every 
shape  between  rectilinear  and  spinal.  Most  of  them  are 
microscopic,  but  some  are  of  considerable  size,  as  the  Or- 
bitolites,  which  are  found  in  tertiary  limestones  in  Malabar. 
The  Nummulitic  limestone,  which  extends  over  large  areas 
of  both  hemispheres,  and  of  which  the  pyramids  of  Egypt 
are  built,  is  composed  of  the  remains  of  the  genus  Num- 
mulina;  and  the  Eozoon  Canadense  has  been  shown  by 
Drs.  Dawson  and  Carpenter  to  belong  to  the  Foramini- 
feral  type. 

In  some  Foraminifera  the  true  shell  is  replaced  by  a 
sandy  envelope,  whose  particles  are  often  cemented  by 
phosphate  of  iron.  Dr.  Carpenter,  whose  researches  have 
largely  extended  our  knowledge  of  this  group,  pertinently 
remarks  that  "there  is  nothing  more  wonderful  in  nature 
than  the  building  up  of  these  elaborate  and  symmetrical 
structures  by  mere  jelly  specks,  presenting  no  trace  what- 
ever of  that  definite  'organization'  which  we  are  accus- 


160  THE    MICROSCOPIST. 

tomed  to  regard  as  necessary  to  the  manifestations  of 
conscious  life."* 

The  Polycystina,  like  the  Foraminifera,  are  beautiful 
objects  for  the  binocular  microscope,  with  the  black- 
ground  illumination  by  the  Webster  condenser,  the  spot- 
lens,  or  the  paraboloid. 

The  Porifera  or  sponges  begin  life  as  solitary  Amoeba, 
and  amid  aggregations  formed  by  their  multiplication, 
the  characteristic  spicules  of  sponge-structure  make  their 
appearance.  In  one  group,  the  skeleton  is  a  siliceous 
framework  of  great  beauty.  In  Hyalonema,  the  silica  is 
in  bundles  of  long  threads  like  spun  glass.  Sometimes 
sponge  spicules  are  needle-like,  straight  or  curved,  pointed 
at  one  or  both  ends ;  sometimes  with  a  head  like  a  pin, 
furnished  with  hooks,  or  variously  stellate.  Dr.  Carpen- 
ter thinks  it  probable  that  each  spicule  was  originally  a 
segment  of  sarcode,  which  has  undergone  either  calcifica- 
tion or  silicification  (Plate  XII,  Fig.  118). 

III.  INFUSORIAL  ANIMALCULES. — From  the  earliest  his- 
tory of  the  microscope,  the  minute  animals  found  in  vari- 
ous infusions  or  in  stagnant  pools,  etc.,  have  attracted 
attention.  We  owe  to  Professor  Ehrenberg  the  first  sci- 
entific arrangement  of  this  class,  and  although  more  ex- 
tended observations  have  changed  his  classification,  yet 
many  of  his  views  are  still  accepted  by  the  most  recent 
investigators.  Ehrenberg  divided  this  class  into  two 
groups,  which  represent  very  different  grades  of  organi- 
zation. The  first  he  called  Polygastrica  (many-stomached) 
from  a  view  of  their  structure,  which  subsequent  examin- 
ations have  not  confirmed.  The  other  group  is  that  of 
JRotifera  or  Rotatoria,  a  form  of  animal  life  which  is  most 
appropriately  classed  among  worms.  The  term  Infusoria 
is  now  applied  to  those  forms  which  Professor  Ehrenberg 

*  The  Microscope  and  its  Revelations,  by  W.  B.  Carpenter,  M.D., 
LL.D.,  etc. 


PLATE  XII. 


FIG.  115. 


FIG. 116. 


Monera  (Amoeba). 


A,  Difflugiaproteiformis;  -B,Diffl,ugiaoblonga;  c,Arcella 
acuminata;  D,  Arcella  dentata. 


Gromiaoviformis^iih  its  pseudopodia  extended. 


FIG.  118. 


Structure  of  Grantia  compressa:  B,  small  portion  highly  magnified. 


THE  MICROSCOPE  IN  ZOOLOGY.          161 

called  polygastric  animalcules.  .  Yet  a  large  section  de- 
scribed by  him  in  this  connection,  including  the  Desmidi- 
acece,  Diatomacece,  Volvocinece,  and  other  protophytes,  have 
been  transferred  by  naturalists  to  the  vegetable  kingdom. 

The  bodies  of  the  Infusoria  consist  of  sarcode  or  bio- 
plasm, having  an  outer  layer  of  firmer  consistence.  Some- 
times the  integument  is  hardened  on  one  side  so  as  to  form 
a  shield,  and  in  other  cases  it  is  so  prolonged  and  doubled 
upon  itself  as  to  form  a  sheath  or  cell,  within  which  the 
animalcule  lies.  The  form  of  the  body  is  more  definite 
than  that  of  Amoeba,  so  as  to  be  characteristic  of  species. 
It  may  be  oblong,  oval,  or  round ;  and  some  kinds,  as 
Vorticella,  are  attached  to  a  footstalk,  which  has  the  power 
of  contracting  in  a  spiral  coil.  ~No  distinct  muscular 
structure  can  be  detected  in  the  Infusoria,  yet  the  general 
substance  of  the  body  is  contractile.  In  most  species 
short  hair-like  filaments  or  cilia  project  from  the  surface, 
sometimes  arranged  in  one  or  more  rows  round  the  mouth, 
and  moving  to  all  appearance  under  the  influence  of  voli- 
tion. In  others  there  are  one  or  two  flagelliform  filaments, 
or  long  anterior  cilia  with  vibratile  ends.  Others,  again, 
have  setse  or  bristles,  which  assist  in  locomotion.  The 
motions  of  some  are  slow,  and  of  others  quite  rapid. 

The  interior  of  the  sarcode  body  exhibit  certain  round- 
ish spots,  sometimes  containing  Diatoms  or  other  foreign 
substances.  They  have  been  called  gastric  vesicles,  cells, 
spaces,  or  sacculi.  They  are  only  visible  from  their  con- 
tents, and  seem  to  be  mere  spaces  without  a  living  mem- 
brane. If  a  little  indigo  or  carmine  is  diffused  in  the 
water  which  contains  the  Infusoria,  the  cavities  will  soon 
be  filled  and  become  distinct.  If  watched  carefully  they 
will  appear  to  move  round  the  body  of  the  animal,  and  as 
the  pigment  escapes  at  some  part  of  the  surface,  the  spots 
will  disappear.  Ehrenberg  regarded  these  spots  as  so 
many  stomachs  arranged  about  a  common  duct,  but  the 
common  opinion  at  present  regards  them  as  temporary 

11 


162  THE    MICROSCOPIST. 

digestive  sacs  made  by  the  inclosure  of  food  by  the  soft 
bioplasm. 

In  addition  to  the  "vacuoles"  described,  contractile 
vesicles  are  seen  which  contract  and  dilate  rhythmically, 
and  do  not  change  their  position.  They  have  been  con- 
sidered to  serve  for  respiration. 

Most  of  the  Infusoria  multiply  by  self-division  (Plate 
XIII,  Fig.  119),  and  at  certain  times  undergo  an  encyst- 
ing process,  much  resembling  the  "  still "  condition  of  Pro- 
tophytes,  and  like  that  serving  for  preservation  under 
circumstances  which  are  unfavorable  to  ordinary  vital 
activity.  The  gemmules  or  progeny  which  result  from 
the  bursting  of  the  cyst  do  not  always  resemble  the  parent 
in  form.  The  recent  researches  of  Drs.  Dallinger  and 
Drysdale  have  shown  considerable  variety  in  the  life  his- 
tory of  the  Infusoria.  In  some  instances  the  product  of 
the  encysting  process  was  not  a  mass  of  granules,  but  an 
aggregation  of  minute  germinal  particles  not  more  than 
sWotJoth  °f  an  incn  in  diameter,  and  capable  of  resisting 
heat,  either  by  boiling  or  by  dry  heating  up  to  300°  F. 

The  observations  of  M.  Balbiani  show  that  in  many  of 
the  Infusoria,  male  and  female  organs  are  combined  in 
the  same  individual,  but  that  a  congress  of  two  is  neces- 
sary for  the  impregnation  of  the  ova,  those  of  each  being 
fertilized  by  the  spermatozoa  of  the  other. 

There  is  also  a  curious  tribe  of  suctorial  animalcules 
called  Acinetce,  which  put  forth  tubular  prolongations 
which  penetrate  the  bodies  of  other  species  and  grow  in 
their  interior  as  parasites. 

The  systematic  arrangement  of  the  Infusoria  is  yet 
unsettled.  Ehrenberg's  families,  excluding  those  now 
placed  among  Algse  or  Rhizopods,  are  as  follows : 


THE  MICROSCOPE  IN  ZOOLOGY.          163 

A.  Intestinal  tube  absent. 

Body  variable,  without  cilia. 

Carapace  absent,  .  _    '. .    "    ,       . ,        .     ASTASI^A. 

Carapace  present,  .         .         ...     DINOBRYINA. 
Cilia  or  seta3  present. 

Carapace  absent,  ...        .        :•-•.•     CYCLIDINA. 

Carapace  present,  .        >   '     .        .        .     PERIDIN^A. 

B.  Intestinal  tube  present. 

Orifice  single. 

Carapace  absent,    .     #  ..       ;"      .        .     VORTICELLINA. 
Carapace  present,  .         .        .;        .    .    .     OPHRYDINA. 
Two  opposite  orifices. 

Carapace  absent,     ....        .        .     ENCHELIA. 

Carapace  present,  .         .         .,       .         .     COLEPINA. 
Orifices  differently  placed. 
Carapace  none. 

No  tail,  but  a  proboscis,         .>        .     TRACHELINA. 
Tail  present,  mouth  anterior,          .     OPHRYOCERCINA. 
Carapace  present,  .        .        .••/...     ASPIDISCINA. 
Orifices  ventral. 

Carapace  absent. 

Motion  by  cilia,       ....     COLPODEA. 

Motion  by  organs,  ....     OXYTRICHINA. 

Carapace  present,  .         .         .        .        .     EUPLOTA. 


IV.  ROTATORIA  OR  WHEEL  ANIMALCULES. — These  are 
microscopic,  aquatic,  transparent  animals,  of  a  higher 
organization  than  the  Infusoria,  and  belonging  in  all 
probability  to  the  class  Vermes.  Their  chief  interest  to 
the  microscopist  is  derived  from  the  possession  of  a  more 
or  less  lobed,  retractile  disk,  covered  with  cilia,  which, 
when  in  motion,  resemble  revolving  wheels.  They  have 
also  a  complicated  dental  apparatus,  and  generally  a  dis- 
tinct alimentary  canal,  and  are  reproduced  by  ova.  Some 
are  more  or  less  covered  by  a  carapace,  and  in  most  there 
is  a  retractile  tail-like  foot,  sometimes  terminated  by  a 
suctorial  disk  or  a  pair  of  claw-like  processes.  The  ner- 
vous and  vascular  systems  are  not  well  known,  although 
traces  of  them  are  seen.  The  young  of  some  possess  an 
eye  which  often  disappears  in  the  adult.  They  are  re- 


164  THE    MICROSCOPIST. 

markably  tenacious  of  life,  having  in  some  instances  re- 
vived after  having  been  kept  dry  for  several  years. 

M.  Dujardin  divides  the  Rotifera  into  four  groups  or 
natural  families : 

1.  Those  attached  by  the  foot,  which  is  prolonged  into 
a  pedicle.     It  includes  two  families,  the  Floscularians  and 
the  MdicertianS)  in  the  first  of  which  the  sheath  or  cara- 
pace is  transparent,  and  in  the  other  composed  of  little 
rounded  pellets  (Plate  XIII,  Fig.  120). 

2.  The  common  Rotifer  and  its  allies,  which  swim  freely 
or  attach  themselves  by  the  foot  at  will  (Plate  XIII,  Fig. 
121). 

3.  Those  which  are  seldom  or  never  attached,  the  Bra- 
chionians  and  the  Furcularians.     The  former  are  short, 
broad,  and  flat,  and  inclosed  in  a  sort  of  cuirass ;  the  latter 
are  named  from  a  bifurcated,  forcep-like  foot  (Plate  XIV, 
Fig.  122). 

4.  The  Tardigrada  or   water  bears.     These   have   no 
ciliated  lobes,  but  are  in  other  respects  like  their  allies, 
and  seem  to  be  a  connecting  link  between  the  Rotifers 
and  worms.     The  segments  of  the  body,  except  the  head, 
bear  two  fleshy  protuberances  furnished  with  four  curved 
hooks.* 

Y.  POLYPS. — The  animals  of  this  class  were  formerly 
called  Zoophytes,  or  animal  flowers.  They  are  the  most 
important  of  coral-making  animals,  although  the  Hydroids 
and  Bryozoa,  together  with  some  Algae,  as  the  Nullipores, 
share  with  them  the  formation  of  coral,  which  is  a  secre- 
tion of  calcareous  matter.  Dana's  work  on  corals  gives  a 
classification,  of  which  we  present  a  summary. 

A  good  idea  of  a  polyp  may  be  had  from  comparison 
with  the  garden  aster,  the  most  common  form  of  a  polyp 
flower  being  a  disk  fringed  with  petal-like  organs  called 
tentacles. 

The  internal  structure,  like  the  external,  is  radiate,  and 

*  Carpenter  on  the  Microscope. 


PLATE  XIII. 


FIG. 119. 


Fissiparous  multiplication  of  Chilodon  cucullvlus. 


FIG.  120. 


FIG.  121. 

B  A 


Rodifer  vulgaris,  as  seen  at  A,  with 
the  wheels  drawn  in,  and  at  B  with 
the  wheels  expanded;  a,  mouth;  6, 
eye-spots;  c,  wheels;  d,  calcar  (an- 
tenna?); e,  jaws  and  teeth;  /,  ali- 
mentary canal ;  g,  glandular  (?)  mass 
enclosing  it;  h,  longitudinal  mus- 
cles ;  i,  i,  tubes  of  water  vascular 
system;  k,  young  animal;  /.cloaca. 


Stephanoceros  Eichornii. 


THE  MICROSCOPE  IN  ZOOLOGY.          165 

the  cavity  of  the  body  is  divided  by  septa  into  narrow 
compartments.  The  walls  contain  circular  and  longitu- 
dinal muscles,  which  serve  for  contraction  of  the  body, 
which  is  afterwards  expanded  by  an  injection  or  absorp- 
tion of  water  by  the  mouth. 

The  most  interesting  part  of  the  structure  of  these 
animals,  to  the  microscopist,  is  the  multitude  of  lasso-cells, 
called  also  nettling -cells,  thread  capsules,  and  cnidce,  which 
stud  the  tentacles  and  other  parts  of  the  body,  and  by 
means  of  which  the  prey  of  the  polyp  is  at  once  pierced 
and  poisoned.  A  small  piece  of  the  tentacle  of  a  sea 
anemone  placed  in  a  compressorium  under  the  microscope, 
and  subjected  to  gentle  pressure,  will  show  the  protrusion 
of  many  little  dart-like  processes  attached  to  thread-like 
filaments.  Many  observations  indicate  the  injection  of  a 
poison  through  these  darts,  which  is  instantly  fatal  to 
small  animals  (Plate  XIV,  Fig.  123). 

The  polyp  has  no  circulating  fluid  but  the  results  of 
digestion  mixed  with  salt  water,  no  bloodvessels  but  the 
vacuities  among  the  tissues,  and  no  passage  for  excrements 
except  the  mouth  and  the  pores  of  the  body.  Reproduc- 
tion is  both  by  ova  and  by  buds. 

I.  Actinoid  polyps  are  related  to  the  Actinea  or  sea 
anemone.     The  number  of  tentacles  and  interior  septa 
is  a  multiple  of  six. 

II.  Cyathophylloid  polyps  have  the  number  of  tentacles 
and  septa  a  multiple  of  four. 

III.  Alcyonoid  polyps  have  eight  fringed  tentacles.    The 
Alcyonium  tribe  are  among  the  most  beautiful  of  coral 
shrubs.     The  Gorgonia  tribe  has  reticulated  species  like 
the  sea  fan,  and  bears  minute  calcareous  spicules,  often 
brilliantly  colored.     The  Pennatula  tribe  is  unattached, 
and  often  rod-like,  with  the  polyps  variously  arranged. 

VI.  HYDROIDS. — The  type  of  this  class  is  the  common 
Hydra,  which  is  often  found  attached  to  leaves  or  stems 
of  aquatic  plants,  etc.  It  is  seldom  over  half  an  inch  long. 


166  THE    MICROSCOPIST. 

It  has  the  form  of  a  polyp,  with  long  slender  tentacles. 
Besides  these  tentacles  with  their  lasso-cells,  it  has  no 
special  organs  except  a  mouth  and  tubular  stomach.  Like 
the  fabled  Hydra,  if  its  head  be  cut  off  another  will  grow 
out,  and  each  fragment  will  in  a  short  time  become  a  per- 
fect animal,  supplying  whatever  is  wanting,  hence  its  name 
(Plate  XIV,  Fig.  124).  The  Hydra  has  the  power  of  lo- 
comotion, bending  over  and  attaching  its  head  until  the 
tail  is  brought  forward,  somewhat  after  the  manner  of  a 
leech. 

Compound  Hydroids  may  be  likened  to  a  Hydra  whose 
buds  remain  attached  and  develop  other  buds  until  an 
arborescent  structure,  called  a  polypary,  is  produced.  The 
stem  and  branches  consist  of  fleshy  tubes  with  two  layers, 
the  inner  one  having  nutritive  functions,  and  the  outer 
secreting  a  hard,  calcareous,  or  horny  layer.  The  indi- 
viduals of  the  colony  are  of  two  kinds,  the  pdypite  or 
nutritive  zooid,  resembling  the  Hydra,  and  the  gonozooid, 
or  sexual  zooid,  developed  at  certain  seasons  in  buds  of 
particular  shape. 

To  mount  compound  Hydrozoa,  or  similar  structures, 
place  the  specimen  alive  in  a  cell,  and  add  alcohol  drop 
by  drop  to  the  sea-water ;  this  will  cause  the  animals  to 
protrude  and  render  their  tentacles  rigid.  Then  replace 
the  alcohol  with  Goadby's  solution,  dilute  glycerin,  or 
other  preserving  fluid. 

VII.  ACALEPIIS,  or  sea-nettles,  are  of  all  sizes,  from  an 
almost  invisible  speck  to  a  yard  in  diameter.  They  swarm 
in  almost  every  sea,  and  are  frequently  cast  upon  the 
beach  by  the  waves.  They  are  transparent,  floating  free, 
discoid  or  spheroid,  often  shaped  like  a  mushroom  or  um- 
brella, and  their  organs  are  arranged  radiately  round  an 
axis  occupied  by  the  pedicle  or  stalk.  They  are  furnished 
with  muscular,  digestive,  vascular,  and  nervous  systems. 
They  were  formerly  divided  into 

1.  Pulrnonigrada,  from  their  movements  being  effected 


PLATE  XIV. 

FIG.  122. 


Nolens  quadricornis :— A,  dorsal  view  ;  B,  side  view. 


Hydra  jusca  in  gemmation. 


Filiferous  capsules  of  Helianthoid  Polypes :— A,B, 
Corynactis  Allmanni;  c,  E,  F,  Caryophyllia  Smithii ; 
D,  G,  Actinia  crass icornis;  H,  Actinia  Candida. 


THE    MICROSCOPE    IN    ZOOLOGY.  167 

by  a  rhythmical  contraction  and  dilation,  as  in  Rhizistoma, 
etc.  2.  Cilograda,  moving  by  narrow  bands  of  vibratile 
cilia  variously  disposed  over  the  body.  In  Beroe  the  cilia 
are  transformed  into  flat  fin-like  shutters,  arranged  in 
eight  longitudinal  bands.  InVenus's  girdle,  Cesium  Ve- 
neriS)  the  margins  of  a  gelatinous  ribbon  are  fringed  with 
cilia.  3.  Physograda,  which  move  by  means  of  an  expan- 
sile bladder,  as  the  Physalia,  or  Portuguese  man  of  war. 
4.  Cirrigrada,  possessing  a  sort  of  cartilaginous  skeleton, 
and  furnished  with  appendages  called  cirri,  serving  as  oars 
and  for  prehension,  as  Porpita  and  Velella.  In  the  latter 
there  is  also  a  subcartilaginous  plate  rising  at  right  angles 
from  the  surface  supporting  a  delicate  membrane,  which 
acts  as  a  sail. 

This  classification  has  been  laid  aside  since  the  micro- 
scopic discovery  of  the  close  relationship  between  the 
Hydrozoa  and  the  Medusoid  Acalephs,  and  the  latter  are 
now  subdivided  into  the  "  naked-eyed  "  and  the  "  covered- 
eyed  "  Acalephs.  The  alternation  of  generations,  page 
126,  is  fully  illustrated  in  this  class.  The  embryo  emerges 
as  a  ciliated  gemmule,  resembling  one  of  the  Infusoria. 
One  end  contracts  and  attaches  itself  so  as  to  form  a  foot, 
while  the  other  enlarges  and  becomes  a  mouth,  from  which 
four  tubercles  sprout  and  become  tentacles.  Thus  a  Hy- 
dra-like polyp  is  formed,  which  acquires  additional  tenta- 
cles. From  such  a  polyp  many  colonies  may  rise  by  gem- 
mation or  budding,  but  after  a  time  the  polyp  becomes 
elongated,  and  constricted  below  the  mouth.  The  con- 
stricted part  gives  origin  to  other  tentacles,  while  similar 
constrictions  are  repeated  round  the  lower  parts  of  the 
body,  so  as  to  divide  it  into  a  series  of  saucer-like  disks, 
which  are  successively  detached  and  become  Medusae 
(Plate  XV,  Figs.  125,  126). 

VIII.  ECHINODERMS. — This  class  includes  the  star-fishes, 
the  sea-urchins  or  sea-eggs,  the  sea-slugs,  and  the  crinoids 
or  stone  lilies  of  former  ages.  If  we  imagine  a  polyp  with 


168  THE    MICROSCOPIST. 

a  long  stem  to  secrete  calcareous  matter,  not  merely  exter- 
nally, but  in  the  substance  of  its  body  and  tentacles,  such 
polyp  when  dried  would  present  some  such  appearance  as 
the  fossil  Encrinoid  Echinode'rms  of  past  times.  The  im- 
agination of  such  a  polyp  without  a  stem,  and  having 
sucker-like  disks  on  its  arms,  will  give  us  the  picture  of 
a  star-fish  (Asterias).  Imagine  the  rays  diminished  and 
the  central  part  extended,  either  flat  or  globular,  and  we 
have  the  form  of  Echini  with  the  spines  removed.  The 
Holothurice  have  elongated  membranous  bodies,  with  im- 
bedded spiculse. 

The  structure  of  Echinoderms  is  quite  complex,  and 
belongs  to  comparative  anatomy  rather  than  microscopy, 
yet  some  directions  for  the  study  of  these  forms  is  essen- 
tial to  our  plan. 

Thin  sections  of  the  shells,  spines,  etc.,  may  be  made  by 
first  cutting  with  a  fine  saw,  and  rubbing  down  with  a 
flat  file.  They  should  be  smoothed  by  rubbing  on  a  hone 
with  water,  cemented  to  a  glass  slip  with  balsam,  and 
carefully  ground  down  to  the  required  thickness.  They 
may  be  mounted  in  fluid  balsam. 

Many  Echinoderms  have  a  sort  of  internal  skeleton 
formed  of  detached  plates  or  spiculse.  The  membranous 
integument  of  the  Holothurise  have  imbedded  calcareous 
plates  with  a  reticulated  structure,  and  they  are  often 
furnished  with  appendages,  as  prickles,  spines,  hooks,  etc., 
which  form  beautiful  microscopic  objects. 

The  larva  of  an  Echinoderm  is  a  peculiar  zooid,  which 
develops  by  a  sort  of  internal  gemmation.  One  of  the 
most  remarkable  of  these  larvae  has  been  called  Bipin- 
naria. 

IX.  BRYOZOA  OR  POLYZOA. — Microscopic  research  has 
removed  this  class  from  the  polyps,  which  they  resemble, 
to  the  molluscan  sub-kingdom.  They  have  a  group  of 
ciliated  tentacles  round  the  mouth,  but  have  a  digestive 
system  far  more  complex  than  polyps.  They  form  delicate 


PLATE  XV. 


FIG.  125. 


FIG.  127. 


• 


Development  of  Medusa  buds  in  Syn- 
choryna  Snrsii. 

FIG  126. 


A,  Portion  of  Cellularia  ciliata,  enlarged ;  B, 
one  of  the  "  bird's-head  "  of  Bvgula  avicularia, 
more  highly  magnified,  and  seen  in  the  act  of 
grasping  another. 


FIG.  128. 


Successive  stages  of  development  of  Medusa 
buds  from  Slrobila  larva. 


Sertularia  cupressina :— A,  natural  size; 
B,  portion  magnified. 


THE  MICROSCOPE  IN  ZOOLOGY.          169 

corals,  either  membranous  or  calcareous,  made  up  of  minute 
cabin-like  cells,  which  are  either  thin  crusts  on  sea-weeds, 
rocks,  etc.,  or  slender  moss-like  tufts,  .or  groups  of  thin 
curving  plates,  or  net-like  fronds,  and  sometimes  thread- 
like lines  or  open  reticulations.  The  cells  of  a  group  have 
no  connection  with  a  common  tube,  as  the  Hydroids,  but 
the  alimentary  system  of  each  little  Bryozoon  is  indepen- 
dent. 

Many  of  the  Polyzoa  have  curious  appendages  to  their 
cells,  of  two  kinds ;  the  first  are  called  birds'-head  pro- 
cesses or  avicularia.  They  consist  of  a  body,  a  hinge  or 
lower  jaw-like  process,  and  a  stalk.  The  lower  portion  is 
moved  by  an  elevator  and  depressor  muscle,  and  during 
life  the  motion  is  constant.  The  second  kind,  or  vibracula, 
is  a  hollow  process  from  which  vibratile  filaments  project 
(Plate  XV,  Figs.  127,  128). 

X.  TUNICATA. — These  molluscs  are  so  named  from  the 
leathery  or  cartilaginous  tunic  which  envelops  them,  and 
which  often  contains  calcareous  spicula.  Like  the  Bryo- 
zoa  they  tend  to  produce  composite  structures  by  gemma- 
tion, but  they  have  no  ciliated  tentacles.  They  are  of 
most  interest  to  the  microscopist  from  the  peculiar  actions 
of  their  respiratory  and  circulatory  organs,  which  may  be 
seen  through  the  transparent  walls  of  small  specimens. 
The  branchial  or  respiratory  sac  has  a  beautiful  network 
of  bloodvessels,  and  is  studded  with  vibratile  cilia  for  dif- 
fusing water  over  the  membrane.  The  circulation  is  re- 
markable from  the  alternation  of  its  direction. 

The  smaller  Tunicata  are  usually  found  aggregate,  in- 
vesting rocks,  stones  and  shells,  or  sea-weeds ;  a  few  are 
free. 

Synopsis  of  the  Families. 

A.  Attached ;  mantle  and  test  united  only  at  the  ori- 
fices. 

1.  Botryllidce. — Bodies  united  into  systems. 


170  THE    M1CROSCOPIST. 

2.  Clavelinidce. — Bodies  distinct,  but  connected   by  a 
common  root  thread. 

3.  AscidiadcB. — Bodies  unconnected. 

B.  Free ;  mantle  and  test  united  throughout. 

4.  Pelonceadce. — Orifices  near  together. 

5.  Salpadce. — Orifices  at  opposite  ends. 

XI.  CONCHIFERA. — This  class  consists  of  bivalve  mol- 
luscs, and  is  chiefly  interesting  to  the  microscopist  from 
the  ciliary  motion  on  their  gills  and  the  structure  of  the 
shell. 

The  ciliary  motion  may  be  observed  in  the  oyster  or 
mussel,  by  detaching  a  small  piece  of  one  of  the  bands 
which  run  parallel  with  the  edge  of  the  open  shell,  placing 
it  on  a  glass  slide  in  a  drop  of  the  liquid  from  the  shell, 
separating  the  bars  with  needles,  and  covering  it  with 
thin  glass ;  or  the  fragment  may  be  placed  in  the  live  box 
and  submitted  to  pressure.  The  peculiar  movement  of 
each  cilium  requires  a  high  magnifying  power.  It  appears 
to  serve  the  double  purpose  of  aeration  of  the  blood  and 
the  production  of  a  current  for  the  supply  of  aliment. 

Dr.  Carpenter  has  shown  that  the  shells  of  molluscs 
possess  definite  structure.  In  the  Margaritacece,  the  exter- 
nal layer  is  prismatic,  and  the  internal  nacreous.  The 
nacreous  or  iridescent  lustre  depends  on  a  series  of  grooved 
lines  produced  by  laminae  more  or  less  oblique  to  the  plane 
of  the  surface.  The  shells  of  Terebratulce  are  marked  by 
perforations,  which  pass  from  one  surface  to  another. 
The  rudimentary  shell  of  the  cuttle-fish  (of  the  class 
Cephalopoda),  or  "cuttle-fish  bone,"  is  a  beautiful  object 
either  opaque  or  in  the  polariscope.  Sections  may  be 
made  in  various  directions  with  a  sharp  knife,  and 
mounted  as  opaque  objects  or  in  balsam. 

XII.  GASTEROPODA. — These  molluscs  are  either  naked, 
as  the  slug,  or  have  univalve  shells,  as  the  snail,  the  lim- 
pet, or  the  whelk.     As  in  the  other  classes  referred  to, 
the  details  of  anatomical  structure  are  full  of  interest ; 


PLATE  XVI. 


FIG.  130. 


FIG.  129 


A,  female  of  Cyclops  quadricornis ; — a,  body ;  6,  tail ; 
c,  antenna;  d,  antennule;  e,  feet;  /,  plumose  setae  of 
tail ;— B,  tail,  with  external  egg-sacs  ;  c,  D,  E,  F,  G, 
successive  stages  of  development  of  young. 


FIG.  131. 


Metamorphosis  of  Carcinus  mcenas: — A,  first  stage  ;  B,  second  stage ;  c,  third  stage, 
in  which  it  begins  to  assume  the  adult  form ;  D,  perfect  form. 


THE  MICROSCOPE  IN  ZOOLOGY.          171 

but  to  the  microscopist  the  palate,  or  tongue  as  it  is  called 
— a  tube  which  passes  beneath  the  mouth,  opening  ob- 
liquely in  front,  and  which  is  covered  with  transverse 
rows  of  minute  teeth  set  upon  plates — presents  characters 
of  great  value  in  classification.  These  palates  require 
careful  dissection,  and  when  niounted  in  balsam  become 
beautiful  polariscope  objects  (Plate  XVI,  Fig.  129). 

XIII.  CEPHALOPODA. — The  crystalline  lens  in  the  eye  of 
the  cuttle-fish  is  said  to  be  of  the  same  form  as  the  well- 
known  "  Coddington  lens."  The  skin  of  this  class  con- 
tains a  curious  provision  for  changing  its  hue,  consisting 
of  large  pigment-cells  containing  coloring  matter  of  vari- 
ous tints. 

The  suckers,  or  prehensile  disks,  on  the  arms  of  cephal- 
opods  often  make  interesting  opaque  objects  when  dried. 

XIY.  ENTOZOA. — These  are  parasitic  animals  belonging 
to  the  class  of  worms.  They  are  characterized  by  the 
absence  or  low  development  of  the  nutritive  system,  and 
the  extraordinary  development  of  their  reproductive  or- 
gans. Thus  the  Tcenia  or  tapeworm  has  neither  mouth 
nor  stomach,  the  so-called  "  head"  being  merely  an  organ 
for  attachment,  while  each  segment  of  the  "  body  "  con- 
tains repetitions  of  a  complex  generative  apparatus. 

Among  the  Nematoid  or  roundworms,  the  Anguillulce, 
or  little  eel-like  worms,  found  in  sour  paste,  vinegar,  etc., 
as  well  as  the  Trichina  spiralis,  inhabiting  the  voluntary 
muscles,  are  generally  classified. 

ORDER  I.  STERELMINTHA. — Alimentary  canal  absent  or 
indistinct. 

FAMILY  1.  Cestoidea. — Tapeworms;  body  strap-shaped, 
divided  into  transverse  joints ;  alimentary  canal  indistinct. 
The  cystic  Entozoa  (Echinococcus,  etc.)  are  nurse  or  larval 
forms  of  Cestoidea. 

FAMILY  2.  Trematoda. — Body  mostly  flattened ;  alimen- 
tary canal  distinct ;  branched. 


172  THE    MICROSCOPIST. 

FAMILY  3.  Acanthocephala. — Body  flattened,  transversely 
wrinkled  ;  sexual  organs  in  separate  individuals. 

FAMILY  4.  Gordiar.ea  (Hairworms). — Body  filamentous, 
cylindrical ;  alimentary  canal  present ;  sexes  distinct. 

FAMILY  5.  Protozoidea  or  Gregarinida. — Probably  larval 
forms. 

ORDER  II.  C^LELMINTHA. — Alimentary  canal  distinct. 

FAMILY  1.  Nematoidea  (Roundworms). — Body  cylindri- 
cal, hollow ;  sexes  separate. 

The  Enoplidce  tribe  is  distinguished  by  an  armature  of 
hooks  or  styles  round  the  mouth.  Most  of  them  are 
microscopic. 

XY.  ANNULATA  (Red-blooded  Worms). — Some  of  these, 
as  the  Serpula,  etc.,  are  inclosed  in  tubes  formed  of  a  shelly 
secretion,  or  built  up  of  grains  of  sand,  etc.,  agglutinated 
together.  Many  have  special  respiratory  appendages  to 
their  heads,  in  which  the  microscope  will  exhibit  the  cir- 
culation. The  worms  of  the  Nais  tribe,  also,  are  so  trans- 
parent as  to  be  peculiarly  fitted  for  microscopic  study  of 
structure.  The  dental  apparatus  of  the  leech  consists  of 
a  triangular  aperture  in  a  sucking  disk,  furnished  with 
three  semicircular  horny  plates,  each  bordered  with  a  row 
of  eighty  to  ninety  teeth,  which  act  like  a  saw. 

ORDER  1.  TURBELLARIA. — Body  bilateral,  soft,  covered 
with  vibratile  cilia,  not  segmented ;  eyes  distinct ;  sexless 
or  hermaphrodite. 

ORDER  2.  SUCTORIA  (Apoda). — Body  elongate,  ringed, 
without  bristles  or  foot-like  tubercles;  locomotion  by 
sucking-disks  ;  no  external  branchiae. 

ORDER  3.  SETIGRADA  (Choetopoda). — Body  ringed,  elon- 
gate, with  feet  or  setigerous  rudiments  of  them  ;  external 
branchise  usually  present. 

XVI.  CRUSTACEA. — In  the  family  of  Isopoda  the  micros- 
copist  will  find  the  Ascellus  vulgaris,  or  water  wood-louse, 
of  great  interest,  as  readily  exhibiting  the  dorsal  vessel 
and  circulating  fluids. 


THE    MICROSCOPE    IN    ZOOLOGY.  173 

The  family  of  Entomostraca  contains  a  number  of  gen- 
era, nearly  all  of  which  are  but  just  visible  to  the  naked 
eye.  They  are  distinguished  by  the  inclosure  of  the  body 
in  a  horny  or  shelly  case,  often  resembling  a  bivalve  shell, 
though  sometimes  of  a  single  piece.  The  tribe  of  Lophy- 
ropoda  (bristly -footed),  or  "  water-fleas,"  is  divided  into 
two  orders,  the  first  of  which,  Q&tracoda,  is  characterized 
by  a  bivalve  shell,  a  small  number  of  legs,  and  the  absence 
of  an  external  ovary.  A  familiar  member  of  this  order, 
the  little  Cypris,\$  common  in  pools  and  streams, and  may 
be  recognized  by  its  two  pairs  of  antennae,  the  first  of 
which  is  jointed  and  tufted,  while  the  second  is  directed 
downwards  like  legs.  It  has  two  pairs  of  legs,  the  poste- 
rior of  which  do  not  appear  outside  the  shell. 

The  order  Copepoda  has  a  jointed  shell,  like  a  buckler, 
almost  inclosing  the  head  and  thorax.  To  this  belongs 
the  genus  Cyclops  (named  from  its  single  eye),  the  female 
of  which  carries  on  either  side  of  the  abdomen  an  egg 
capsule,  or  external  ovarium,  in  which  the  ova  undergo 
their  earlier  stages  of  development  (Plate  XVI,  Fig.  130). 

The  Daphnia  pulex,  or  arborescent  water-flea,  belongs  to 
the  order  Gladocera  and  tribe  Branchiopoda.  The  other 
order  of  this  tribe,  the  Phyllopoda,  has  the  body  divided 
into  segments,  furnished  with  leaf-like  members  or  "  fin 
feet." 

When  first  hatched,  the  larval  Entomostraca  differ 
greatly  from  the  adult.  The  larval  forms  of  higher 
Crustacea  resemble  adult  Entomostraca. 

The  suctorial  Crustacea,  order  Siphonostoma,  are  gener- 
ally parasitic,  mostly  affixed  to  the  gills  of  fishes  by  means 
of  hooks,  arms,  or  suckers,  arising  from  or  consisting  of 
modified  foot-jaws.  The  transformations  in  this  order,  as 
in  the  Lerncea,  seem  to  be  a  process  of  degradation.  The 
young  comes  from  the  egg  as  active  as  the  young  of 
Cyclops,  which  they  resemble,  and  pass  through  a  series 
of  metamorphoses  in  which  they  cast  off  their  locomotive 


174  THE    MICROSCOPIST. 

members  and  their  eyes.  The  males  and  females  do  not 
resemble  each  other. 

The  order  Cirrhipeda  consists  of  the  barnacles  and  their 
allies.  In  their  early  state  they  resemble  the  Entomos- 
traca,  are  unattached,  and  have  eyes.  After  a  series  of 
metamorphoses  they  become  covered  with  a  bivalve  shell, 
which  is  thrown  off;  the  animal  then  attaches  itself  by 
its  head,  which  in  the  barnacle  becomes  an  elongated 
pedicle,  and  in  Balanus  expands  into  a  disk.  The  first 
thoracic  segment  produces  the  "multivalve"  shell,  while 
the  other  segments  evolve  the  six  pairs  of  cirrhi,  which 
are  slender,  tendril-like  appendages,  fringed  with  ciliated 
filaments. 

In  the  order  Amphipoda,  the  Gammarus  pulex,  or  fresh- 
water shrimp,  and  the  Talitrus  saltator,  or  sandhopper, 
may  be  interesting  to  the  microscopist. 

The  order  Decapoda,  to  which  belong  the  crab,  lobster, 
shrimp,  etc.,  is  of  interest,  from  the  structure  of  the  shell 
and  the  phenomena  of  metamorphosis.  The  shell  usually 
consists  of  a  horny  structureless  layer  exteriorly,  an  areo- 
lated  stratum,  and  a  laminated  tubular  substance.  The 
difference  between  the  adult  and  larval  forms  in  this  order 
is  so  great  that  the  young  crab  was  formerly  considered 
a  distinct  germs,  Zoea  (Plate  XVI,  Fig.  131). 

For  the  preservation  of  specimens  of  Crustacea,  Dr. 
Carpenter  recommends  glycerin  jelly  as  the  best  medium. 

XVII.  INSECTS. — Many  insects  may  be  mounted  dry, 
as  opaque  objects.  They  may  be  arranged  in  position  by 
the  use  of  hot  water  or  steam.  Those  which  are  trans- 
parent enough  may  be  mounted  in  balsam,  and  very  deli- 
cate ones  in  fluid.  To  display  the  external  chitinous  cov- 
ering of  an  entire  insect,  it  may  be  soaked  in  strong  liquor 
potassse,  and  the  internal  parts  squeezed  out  in  a  saucer 
of  water  by  gently  rolling  over  it  a  camel's-hair  brush. 
It  may  be  put  on  a  slide,  and  the  cover  fastened  by  tying 
with  a  thread.  It  should  then  be  soaked  in  turpentine 


THE  MICROSCOPE  IN  ZOOLOGY.         175 

until  quite  transparent,  when  it  may  be  removed,  the  tur- 
pentine partially  drained  off,  and  a  solution  of  balsam  in 
chloroform  allowed  to  insinuate  itself  by  capillary  attrac- 
tion. Gentle  heat  from  a  spirit-lamp  will  be  useful  at  this 
stage  of  the  mounting. 

Small  insects  hardly  need  soaking  in  caustic  potash,  as 
turpentine  or  oil  of  cloves  will  render  them  after  awhile 
quite  transparent,  and  their  internal  organs  are  beautifully 
seen  in  the  binocular  microscope.  Thin  sections  of  insects 
are  instructive,  and  maybe  made  with  a  section-cutter  by 
first  saturating  the  body  with  thick  gum  mucilage,  and 
then  incasing  in  melted  paraffin. 

Many  insects  and  insect  preparations  are  well  preserved 
in  glycerin. 

The  eggs  of  insects  are  often  interesting  objects,  and 
should  be  mounted  in  fluid. 

Wing  cases  of  beetles  are  often  very  brilliant  opaque 
objects.  Some  are  covered  with  iridescent  scales,  and 
others  have  branching  hairs.  Many  are  improved  by 
balsam,  and  this  may  be  determined  by  touching  with 
turpentine  before  mounting. 

Scales  of  Lepidoptera,  etc.,  may  be  exhibited  in  their 
natural  arrangement  by  mounting  a  small  piece  of  wing 
dry.  If  desired  as  test  objects,  a  slide  or  thin  cover,  after 
having  been  breathed  on,  may  be  slightly  pressed  on  the 
wing  or  body  of  the  insect.  The  scales  are  really  flattened 
cells,  analogous  to  the  epidermic  cells  of  higher  animals. 
Some  have  their  walls  strengthened  by  longitudinal  ribs, 
while  others,  as  the  Podurce,  show  a  beaded  appearance 
under  high  powers  from  corrugation.  Dr.  Carpenter  be- 
lieves the  exclamation  marks  in  the  scales  of  the  latter  to 
be  the  most  valuable  test  of  the  excellence  of  an  objective. 

Hairs  of  insects  are  often  branched  or  tufted.  The  hair 
of  the  bee  shows  prismatic  colors  if  the  chromatic  aberra- 
tion of  the  object-glass  is  not  exactly  neutralized. 

Antennce  vary  greatly  in  form,  and  are  often  useful  in 


176  THE    MICROSCOPIST. 

classification  (Plate  XVII,  Fig.  132).  Thus  in  the  Cole- 
optera  we  have  the  Serricornes,  or  serrated  antennae;  the 
Clavicornes,  or  clubbed  ;  the  Palpicornes,  with  antennae  no 
larger  than  palpi ;  the  Lamellicornes,  with  leaf-like  appen- 
dages to  the  antennae ;  'and  the  Longicornes,  with  antennae 
as  long  or  longer  than  the  body.  Nerve-fibres,  ending  in 
minute  cavities  in  the  antennae,  have  been  traced,  which 
are  supposed  to  be  organs  of  hearing.  The  antennae  should 
be  bleached  to  exhibit  them.  The  bleaching  process  is 
also  useful  for  other  parts  of  insects.  The  bleaching  fluid 
consists  of  a  drachm  of  chlorate  of  potass  in  about  two 
drachms  of  water,  to  which  is  added  about  a  drachm  of 
hydrochloric  acid. 

Compound  eyes  of  insects  are  always  interesting.  They 
are  quite  conspicuous,  and  often  contain  thousands  of 
facets,  or  minute  eyes,  called  ocelli  (Plate  XVII,  A  B,  Fig. 
133).  Besides  these,  insects  possess  rudimentary  single 
eyes,  like  those  of  the  Arachnids.  These  are  at  the  top 
of  the  head,  and  are  termed  stemmata  (Plate  XVII,  a, 
Fig.  133).  To  display  the  "  corneules,"  or  exterior  layer 
of  the  compound  eye,  the  pigment  must  be  carefully 
brushed  away  after  maceration.  A  number  of  notches 
may  then  be  made  around  the  edge,  the  membrane  flat- 
tened on  a  slide,  and  mounted  in  balsam.  Vertical  sec- 
tions may  be  made  while  fresh,  so  as  to  trace  the  relations 
of  the  optic  nerve,  etc.  The  dissecting  microscope  arid 
needles  will  be  found  useful  (Plate  XVII,  Fig.  132). 

Mouths  of  insects  present  great  varieties.  In  the  beetles 
the  mouth  consists  of  a  pair  of  mandibles,  opening  later- 
ally ;  a  second  pair,  called  maxillae ;  a  labrum  or  upper 
lip ;  an  under  lip  or  labium  ;  one  or  two  pairs  of  jointed 
appendages  to  the  maxillae,  termed  maxillary  palpi ;  and 
a  pair  of  labial  palpi.  The  labium  is  often  composed  of 
distinct  parts,  the  first  of  which  is  called  the  mentum  or 
chin,  and  the  anterior  part  the  ligula  or  tongue.  This 
latter  part  is  greatly  developed  in  the  fly,  and  presents 


PLATE  XVII. 


Tongue  of  common  Fly. 


Foot  of  Fly. 


FIG.  136. 


Traeheal  system  of  Nepa  (Water-scorpion). 


THE    MICROSCOPE    IN    ZOOLOGY.  177 

a  curious  modification  of  tracheal  structure,  which  is 
thought  to  serve  the  function  of  suction  (Plate  XVII, 
Fig.  134).  The  tongue  of  the  bee  is  also  an  interesting 
object.  In  the  Diptera  the  labrum,  maxillae,  mandibles, 
etc.,  are  converted  into  delicate  lancets,  termed  setae,  and 
are  used  to  puncture  the  epidermis  of  animals  or  plants, 
from  which  the  juices  may  be  drawn  by  the  proboscis. 
In  the  Lepidoptera  the  labrum  and  mandibles  are  reduced 
to  minute  plates,  while  the  maxillae  are  greatly  elongated, 
and  are  united  to  form  the  haustellum,  or  true  proboscis, 
which  contains  a  tube  for  suction. 

Feet. — These  organs  vary  with  the  habits  of  life  in  dif- 
ferent species.  The  limb  consists  of  five  divisions:  the 
coxa  or  hip,  the  trochanter,  the  femur  or  thigh,  the  tibia 
or  shank,  and  the  tarsus  or  foot.  This  last  has  usually 
five  joints,  but  sometimes  less.  The  Coleoptera  are  subdi- 
vided into  groups,  according  as  the  tarsus  consists  of  five, 
four,  or  three  segments.  The  last  joint  is  furnished  with 
hooks  or  claws,  and  in  the  fly,  etc.,  the  foot  is  also 
furnished  with  membranous  expansions,  called  pulvilli. 
These  latter  have  numerous  hairs,  each  of  which  has  a 
minute  disk  at  its  extremity.  By  these,  probably  by  the 
secretion  of  a  viscid  material,  the  insect  is  enabled  to 
walk  on  glass,  etc.,  in  opposition  to  gravity  (Plate  XVII, 
Fig.  135).  In  the  Dytiscus,  the  inner  side  of  the  leg  is 
furnished  with  disks  or  suckers  of  considerable  size. 
They  may  be  mounted  as  opaque  objects.  Stings  and 
Ovipositors  also  present  a  great  variety  of  structure,  and 
may  be  best  mounted  in  balsam. 

The  alimentary  canal  in  insects  presents  many  diversi- 
ties. As  in  higher  animals,  it  is  shorter  in  flesh-eaters 
than  in  feeders  on  vegetables.  It  consists  of:  1.  The 
oesophagus,  which  is  sometimes  dilated  to  form  a  crop. 

2.  The  muscular  stomach,  or  gizzard,  whose  lining  mem- 
brane is  covered  with  plates,  or  teeth,  for  trituration. 

3.  A  cylindrical  true  stomach,  in  which  digestion  takes 

12 


178  THE    MICROSCOPIST. 

place.  4.  The  small  intestine,  terminating  in  5,  the  large 
intestine  or  colon.  The  colon  of  most  insects  in  the 
imago  or  perfect  state,  never  in  larvae  or  pupse,  contains 
from  four  to  six  organs  of  doubtful  nature  arranged  in 
pairs.  They  are  transparent,  round,  or  oval  tubercles 
projecting  inside  the  colon,  traversed  by  tufts  of  tracheae, 
and  sometimes  with  a  horny  ring  at  the  base. 

The  salivary  glands  are  sacs  or  tubes  of  variable  form 
and  length,  terminating  near  the  mouth.  A  distinct  liver 
is  absent,  its  function  being  performed  by  glandular  cells 
in  the  walls  of  the  stomach.  Many  insects,  however, 
have  ceecal  appendages  to  the  stomach  which  secrete  bile. 
Some  have  tubular  cseca  appended  to  the  small  intestine, 
probably  representing  a  pancreas.  In  the  interspaces  of 
the  various  abdominal  organs,  is  found  a  curious  organ 
called  the  fatty  body,  which  attains  its  development  at 
the  close  of  the  larval  period,  and  appears  to  form  a  res- 
ervoir of  nourishment  for  the  pupa.  It  consists  of  fat- 
cells  imbedded  in  a  reticular  tissue,  and  is  traversed  by 
slender  tracheae. 

The  Malpighian  vessels  are  slender,  mostly  tubular 
glands,  caecal  or  uniting  with  each  other,  w^hich  open  into 
the  pyloric  end  of  the  stomach,  and  as  uric  acid  has  been 
found  in  them,  are  thought  to  serve  the  functions  of  a 
kidney.  Some  consider  the  renal  organ  to  be  represented 
by  certain  long  vessels  convoluted  on  the  colon,  and  open- 
ing near  the  anus. 

Other  glandular  organs  occur  in  insects,  as  cysts  in  the 
integument,  called  glandulse  odoriferse ;  poison  glands, 
attached  to  the  sting  in  many  females ;  and  silk-secreting 
glands,  coiled  in  the  sides  of  the  body  and  opening  out- 
side the  mouth. 

The  heart  is  a  long  contractile  vessel  situated  in  the 
back.  It  is  constricted  at  intervals.  The  posterior  part 
acts  as  a  heart,  and  the  anterior  represents  an  aorta,  and 
conveys  blood  to  the  body.  From  the  anterior  end  the 


THE  MICROSCOPE  IN  ZOOLOGY.          179 

olood  passes  in  currents  in  all  directions,  without  vascular 
walls,  running  into  the  antennae,  wings,  extremities,  etc., 
and  returning  as  a  venous  current,  forming  two  lateral 
currents  towards  the  end  of  the  abdomen,  it  is  brought 
by  the  diastole  of  the  heart  through  lateral  fissures  ex- 
isting in  it. 

The  respiration  is  effected  by  means  of  tracheae,  two 
or  more  large  vessels  running  longitudinally,  giving  off 
branches  in  all  directions,  and  opening  to  the  air  by  short 
tubes,  connected  at  the  sides  of  the  body  with  orifices 
called  spiracles.  Aquatic  larvae  often  have  branchiae  in 
the  form  of  plates,  leaves,  or  hairs,  through  which  the 
tracheae  ramify  (Plate  XVII,  Fig.  136). 

The  nervous  system  consists  of  a  series  of  ganglia  ar- 
ranged in  pairs,  one  for  each  segment  of  the  body.  They 
are  situated  between  the  alimentary  canal  and  the  under 
surface  of  the  body,  and  are  usually  connected  by  longi- 
tudinal nervous  cords.  From  the  ganglia  nerves  are  dis- 
tributed to  all  parts. 

The  muscular  system  of  insects  is  quite  extensive.  Ly- 
onet  dissected  and  described  more  than  four  thousand  in 
the  caterpillar  of  the  goat-moth  (Cossus  ligniperda]. 

XVIII.  ARACHNIDA. — This  class  of  animals  includes 
mites,  ticks,  spiders,  and  scorpions.  They  are  destitute 
of  antennae ;  the  head  and  thorax  are  united ;  they  have 
simple  eyes  (ocelli),  and  eight  jointed  legs. 

The  cheese-mite,  the  u  ticks,"  the  itch-insect  (Sarcoptes 
scabies),  and  the  Demodex  folliculorum,  which  is  parasitic 
in  the  sebaceous  follicles  of  the  skin  of  the  face,  are  com- 
"mon  examples  of  Acari.  They  are  best  mounted  in  fluid. 

The  respiratory  apparatus  in  spiders  differs  from  that 
of  insects,  the  spiracles  opening  into  respiratory  sacs,  which 
contain  leaf-like  folds  for  aeration  of  blood!  The  spinning 
apparatus  is  also  interesting. 

The  minute  anatomy  of  vertebrated  animals  affords  the 


180  THE    MICROSCOPIST. 

microscopist  numerous  specimens,  but  the  details  will  be 
best  understood  from  the  following  chapter. 

As  the  classification  of  the  Invertebrata  is  subject  to 
great  variation,  the  following  table,  after  Nicholson,  is 
added  for  the  sake  of  comparison : 

INVERTEBRATE  ANIMALS. 

SUB-KINGDOM   I. — PROTOZOA. 

CLASS  I.  GREGARINIDJE. — Parasitic  Protozoa,  destitute 
of  a  mouth,  and  destitute  of  pseudopodia.  Ex.,  Gregarina. 

CLASS  II.  RHIZOPODA. — Simple  or  compound  ;  destitute 
of  a  mouth ;  capable  of  putting  forth  pseudopodia. 

CLASS  III.  INFUSORIA. — Generally  with  a  mouth ;  no 
pseudopodia ;  with  vibratile  cilia  or  contractile  filaments. 

SUB-KINGDOM  II. — CCELENTERATA. 

CLASS  I.  HYDROZOA. — Walls  of  the  digestive  sac  not 
separated  from  those  of  the  body  cavity  ;  reproductive 
organs  external. 

Sub-class  1.  Hydroida. — Ex.,  Hydra.  Tubularia  (pipe- 
coralline).  Sertularia  (sea-fir). 

Sub-class  2.  Siphonophora. — Ex.,  Diphyes.  Physalia 
(Portuguese  man-of-war). 

Sub-class  3.  Discophora. — Ex.,  Naked-eyed  Medusae,  or 
Jelly-fish. 

Sub-class  4.  Lucernarida. — Ex.,  Sea-nettles,  or  "  Hidden- 
eyed  "  Medusae. 

CLASS  II.  ACTINOZOA. — Digestive  sac  distinct  from  the 
general  cavity,  but  opening  into  it ;  reproductive  organs 
internal. 

Order  1.  Zoantharia. — Ex.,  Sea- Anemones  (Actinia). 
Reef-building  corals. 

Order  2.  Alcyonaria. — Ex.,  Sea-pen.     Red  coral. 

Order  3.  Ctenophora. — Ex.,  Cestum  (Venus's  girdle). 


THE    MICROSCOPE    IN    ZOOLOGY.  181 

SUB-KINGDOM  III. — ANNULOIDA. 

CLASS  I.  ECHINODERMATA.. — Integument  calcareous  or 
leathery ;  adult  radiate. 

Order  1.  Crinoidea. — Ex.,  Comatula. 

Order  2.  Blastoidea. — (Extinct.) 

Order  3.  Cystoidea. — (Extinct.) 

Order  4.   Ophiuroidea. — Ex.,  Brittle-star. 

Order  5.  Aster oidea. — Ex.,  Star-fish. 

Order  6.  Echinoidea. — Ex.,  Sea-urchins. 

Order  7.  Holothur oidea. — Ex.,  Sea-cucumbers. 

CLASS  II.  SCOLECIDA — Soft-bodied,  cylindrical,  or  flat ; 
nervous  sj^stem  not  radiate  ;  of  one  or  two  ganglia. 

Order  1.   Tceniada. — Ex.,  Tapeworms. 

Order  2.   Trematoda.—Ex.,  Flukes. 

Order  3.   Tarbellaria — Ex.,  Planarians. 

Order  4.  Acantkocephala. — Ex.,  Echinorynchus. 

Order  5.  Gordiacea. — Ex.,  Hairworms 

Order  6.  Nematoda. — Ex.,  Round  worms. 

Order  7.  Rotifera. — Ex.,  Wheel  animalcules. 

SUB-KINGDOM    IV. — ANNULOSA. 

DIVISION  A.  ANARTHROPODA. — Locomotive  appendages 
not  distinctly  jointed  or  articulated  to  the  body. 

CLASS  I.  GEPHYREA. — Ex.,  Spoon-worms. 

CLASS  II.  ANNELIDA.  —  Ex.,  Leeches  (Hirundinidse). 
Earth-worms  (Oligochseta).  Tube-worms  (Tubicola). 
Sand-worms  and  Sea-worms  (Errantia). 

CLASS  III.  CH^ETOGNATHA. — Ex.,  Sagitta. 

DIVISION  B.  ARTHROPODA  —  Locomotive  appendages 
jointed  to  the  body. 

CLASS  I.  CRUSTACEA. — Ex.,  Decapoda.  Isopoda.  Xi- 
phosura.  Cirri  pedia. 

CLASS  II.  ARACHNIDA. — Ex.,  Podosomata  (sea-spiders). 
Acarina  (mites).  Pedipalpi  (scorpions).  Araneida  (spi- 
ders). 


182  THE    MICROSCOPIST. 

CLASS  III.  MYRIAPODA.— Ex.,  Centipedes. 

CLASS  IV.  INSECTA.—  Ex.,  Anoplura  (lice).  Mallophaga 
(bird  lice).  Thysanura  (spring-tails).  Hemiptera.  Or- 
thoptera.  Neuroptera.  Diptera.  Lepidoptera.  Hyme- 
noptera.  Coleoptera. 

SUB-KINGDOM   V. — MOLLUSCA. 

DIVISION  A.  MOLLUSCOIDA. — A  single  ganglion,  or  pair 
of  ganglia ;  heart  imperfect,  or  none. 

CLASS  I.  POLYZOA. — Ex.,  Sea-mats  (Flustra). 

CLASS  II.  TUNICATA. — Ex.,  Ascidia  (Sea-squirts). 

CLASS  III.  BRACHIOPODA. — Ex.,  Terebratula. 

DIVISION  B.  MOLLUSCA  PROPER. — Three  pairs  of  gan- 
glia ;  heart  of  at  least  two  chambers. 

CLASS  I.  LAMELLIBRANCHIATA. — Ex.,  Oyster.     Mussel. 

CLASS  II.  GASTEROPODA.  —  Ex.,  Buccinium.  Helix. 
Doris. 

CLASS  III.  PTEROPODA. — Ex.,  Cleodora. 

CLASS  IY.  CEPHALOPODA. 

Order  1.  Dibranchiata. — Ex.,  Poulp.     Paper  Nautilus. 

Order  2.    Tetrabranchiata. — Ex.,  Pearly  Nautilus. 


CHAPTER   XII. 

THE   MICROSCOPE   IN   ANIMAL   HISTOLOGY. 

IN  Chapter  IX  we  described  the  elementary  living 
substance,  or  bioplasm,  from  which  all  organized  struc- 
tures proceed,  with  an  outline  of  its  morphology,  chemis- 
try, and  physiology.  In  Chapter  X  we  treated  of  Vege- 
table Histology,  or  the  elementary  tissues  and  organs 
which  pertain  to  vegetable  life.  We  now  consider  the 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          183 

structure  of  formed   material   in   animals,  with   special 
reference  to  the    minute  anatomy  of  the  human  body. 
Following  the  generalization  of  Dr.  Beale,  page  118,  we 
may  classify  histological  structures  as  follows  : 
\ 

A.  INORGANIC  AND  ORGANIC  ELEMENTS  OR  PABULUM. 

Eesulting  in 

B.  BIOPLASM  ;  or,  O.  II.  C.  and  K,  with   other  chemical 

elements,  plus,  The  cause  of  life. 
From  this  results : 

C.  FORMED  MATERIAL,  consisting  of, 

I.  CHEMICAL  PRODUCTS  ;  Organic  Compounds,  etc. 

II.  MORPHOLOGICAL  PRODUCTS.   1.  Granules;  2.  Globules; 

3.  Fibres ;  4.  Membrane. 
Forming  Tissues.     1.  Simple  ;  2.  Compound. 
Arranged  in  Organs.     1.  Vegetative  ;  2.  Animal. 

I.  THE  CHEMICAL  PRODUCTS  of  Bioplasm  are  very  nu- 
merous, and  belong  to  the  science  of  Histo-Chemistry. 
Our  plan  allows  us  to  do  little  more  than  to  enumerate 
the  principal  groups.  It  has  already  been  stated  that  the 
true  chemical-  structure  of  bioplasm,  or  living  sarcode, 
(protoplasm  in  a  living  state)  is  unknown,  since  it  is  only 
possible  to  analyze  the  dead  cell  substance.  Of  the  rela- 
tion of  the  oxygen,  hydrogen,  carbon,  and  nitrogen,  etc., 
which  constitute  its  "physical  basis,"  we  can  only  specu- 
late, or  imagine.  See  Chemistry  of  Cells  and  their  Products, 
page  122. 

The  chemical  transformations  of  cell-substance  into 
"  formed  material  "  consist  chiefly,  with  water  and  min- 
eral matter,  of  certain  groups  of  organic  principles,  some- 
times called  albuminous  or  "  protein  "  substances,  and 
their  nearer  derivatives,  as  glutin-yielding  and  elastic 
matter,  with  fat  and  pigments.  These  materials  are  sub- 
ject to  constant  secondary  changes  or  transformations, 


184  THE    MICROSCOPIST. 

since  they  are  not  laid  down  in  the  living  body  once  for 
all.  They  are  also  subject  to  constant  decay,  or  ultimate 
decomposition.  Histo-Chemistry  must,  therefore,  be  always 
a  difficult  study,  since  we  can  rarely  isolate  the  tissues  for 
examination,  nor  always  tell  when  a  substance  is  super- 
fluous aliment,  formative  or  retrogressive  material.  From 
a  limited  number  of  formative  or  histogenic  materials,  we 
have  a  host  of  changed  or  decomposition  products. 

Frey's  Histology  and  Histo-Chemistry,  Strieker's  Hand- 
Book  of  Histology,  and  Beale's  Bioplasm,  are  among  the 
most  useful  books  to  the  student  in  this  department. 

Frey  subdivides  the  groups  of  organic  principles  as  fol- 
lows : 

I.  Albuminous  or  Protein  Compounds. —  Albumen.     Fi- 
brin.   Myosin.    Casein.    Globulin.    Peptones.    Ferments  ? 

II.  Hwmoglobulin. 

III.  Formative  (Histogenic)  Derivatives  from  Albuminous 
Substances. — Keratin.     Mucin.     Colloid.     Glutin-yielding 
substances.    Collagin  and  Glutin.    Chondrigen  and  Chon- 
drin.     Elastin. 

IY.  Fatty  Acids  and  Fats. — Glycerin.  Formic  acid. 
Acetic  acid.  Butyric  acid.  Capronic  acid.  Palmitic  acid. 
Stearic  acid.  Oleic  acid.  Cerebrin.  Cholesterin. 

V.  Carbohydrates. — The  Grape-sugar  group,  Cane-sugar 
group,    and    Cellulose    group ;    or    Glycogen.     Dextrin. 
Grape-sugar.     Muscle-sugar.     Sugar  of  milk. 

VI.  Non-Nitrogenous  Acids. — Lactic.    Oxalic.    Succinic. 
Carbolic.     Taurylic. 

VII.  Nitrogenous    Acids. — Inosinic.     Uric.     Hippuric. 
Glycocholic.     Taurocholic. 

VIII.  Amides,  Amido  Acids,  and  Organic  Bases. — Urea. 
Guanin.     Xanthin.     Allantoin.     Kreatin.     Leucin.     Ty- 
rosin.     Glycin.     Cholin  (KeurinX     Taurin.     Cystin. 

IX.  Animal    Coloring    Matters. — Hsematin.     ILemin. 
Hrematoidin.     Urohsernatin.    Melalin.    Biliary  pigments. 

X.  Cyanogen  Compounds. — Sulpho-cyanogen. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          185 

XI.  Mineral  Constituents. — Oxygen,  Nitrogen,  Carbonic 
acid.  Water.  Hydrochloric  acid.  Silicic  acid.  Calcium 
compounds  (Phosphate,  Carbonate,  Chloride,  and  Fluor- 
ide). Magnesium  compounds  (Phosphate.  Carbonate. 
Chloride).  Sodium  compounds  (Chloride.  Carbonate. 
Phosphate.  Sulphate).  Potassium  compounds  (Chloride. 
Carbonate.  Phosphate.  Sulphate).  Salts  of  Ammonium 
(Chloride.  Carbonate).  Iron  and  its  Salts  (Protochloride. 
Phosphate).  Manganese.  Copper. 

The  subject  of  Histology  relates  properly  to  cell-struc- 
ture (already  described,  Chapter  IX),  and  its  morpho- 
logical products,  yet  its  close  connection  with  Histo-chem- 
istry  renders  the  foregoing  list  of  substances  valuable  to 
the  student. 

II.  HISTOLOGICAL  STRUCTURE  is  due  to  the  formative 
power  of  bioplasm,  or  living  cell-substance,  and  is  not  mere 
selection  and  separation  from  pabulum,  or  aliment,  since 
from  the  same  pabulum,  and,  so  far  as  we  can  see,  under 
the  same  circumstances,  result  tissues  having  different 
physical  and  chemical  properties. 

In  our  classification  we  have  arranged  the  microscopic, 
or  histological,  elements  of  the  tissues  as  Granules,  Glob- 
ules, Fibre,  and  Membrane. 

Granules  are  minute  particles  of  formed  material. 

Globules  are  small,  homogeneous,  round,  or  oval  bodies. 
If  composed  of  albuminous  matter  they  are  rendered  trans- 
parent by  acetic  acid,  and  are  dissolved  by  potash  and 
soda.  If  consisting  of  fat  they  are  soluble  in  ether  and 
unaltered  by  acetic  acid.  If  they  are  earthy  matters  they 
are  dissolved  by  acids  and  unchanged  by  alkalies. 

Fibres  appear  as  fine  lines,  cylindrical  threads,  or  flat- 
tened bands,  parallel,  or  at  various  angles. 

Membrane  is  an  expansion  of  material.  It  may  be  trans- 
parent and  homogeneous,  and  may  be  recognized  by  plaits 
or  folds,  which  sometimes  simulate  fibres,  or  it  may  be 
granular,  or  bear  earthy  particles. 


186  THE    MICROSCOPIST. 

From  these  elements  result  the  simple  and  compound 
tissues. 

The  Simple  Tissues  may  be  divided  into 

1.  Cells   with    intermediate   fluid,   as  Blood,  Lymph, 
Chyle,  Mucus,  and  Pus. 

2.  Epithelium  and  its  appendages. 

3.  Connective    Substances. — Cartilage.     Fat.     Connec- 
tive tissue.     Bone.     Dentine. 

The  Compound  Tissues  are  Muscle,  Nerve,  Gland,  and 
Vascular  tissues. 

These  are  formed  into  Organs. 

1.  Vegetative. — The   Circulatory,  Respiratory,   Diges- 
tive, Urinary,  and  Generative  organs. 

2.  Animal. — The  Bony,  Muscular,  Nervous,  and  Sensory 
apparatus. 

We  shall  attempt  a  brief  description  of  these  tissues 
and  organs,  as  illustrated  by  the  microscope  and  modern 
methods  of  research. 

I.  SIMPLE  TISSUES. 
1.  CELLS  WITH  INTERMEDIATE  FLUID. 

I.   The  Blood. 

The  microscope  shows  blood  to  consist,  especially  in 
man  and  the  higher  animals,  of  red  corpuscles,  colorless 
corpuscles,  and  the  fluid  in  which  they  are  suspended. 

1.  Blood  Plasma,  or  Liquor  Sanguinis. — This  is  a  color- 
less and  apparently  structureless  fluid,  but  when  removed 
from  the  body,  fibrin  separates  from  it  in  solid  form.     In 
small  quantities  of  blood  this  is  seen  in  delicate  fibres 
crossing  each  other  at  various  angles. 

2.  Red-Uood  Corpuscles. — These  were  first  discovered  by 
Svvammerdam,  in  1658,  in  frog's  blood,  and  in  that  of  man 
by  Lewenhoek,  in  1673.     Malpighi  is  said  to  have  first 
seen  the  actual  circulation  of  blood  in  the  web  of  a  frog's 


THE  MICROSCOPE  IN  ANIMAL  HISTOLOGY.    187 

foot.  The  circulation  may  be  readily  observed  by  ether- 
izing a  frog,  and  expanding  its  foot  by  means  of  pins  or 
thread,  upon  the  stage  of  the  microscope  (Plate  XVIII, 
Fig.  137).  The  circulation  may  also  be  seen  in  the  lung, 
mesentery,  or  extended  tongue,  of  the  frog. 

The  red  corpuscles  of  blood  are  flattened  disks,  which 
are  circular  in  Mammals,  except  the  camel  and  lama, 
which  have  elliptic  disks.  In  birds,  amphibia,  and  most 
fishes,  the  disks  are  elliptic.  In  a  few  fishes  (the  cyclos- 
tomata)  they  are  circular.  Their  color  depends  on  hsemo- 
globulin,  which  plays  an  important  part  in  the  exchange 
of  respiratory  gases.  In  man  the  disks  are  usually  double- 
concave,  with  rounded  edges.  Out  of  the  body  they  have 
a  tendency  to  adhere,  or  run  together,  in  chains,  like  rolls 
of  coin  (Plate  XVIII,  Fig.  138).  In  the  elliptic  disks  of 
birds,  etc  ,  there  is  a  distinct  nucleus.  The  size  of  the 
disks  varies.  In  man  they  are  from  0.0045  to  0.0097  mil- 
limetre. The  smallest  disks  are  in  the  Moschus  Javanicus, 
and  the  largest  in  Siren  lacertina.  In  the  latter  they  are 
from  Jg  to  g'o  millimetre. 

It  is  estimated  that  in  a  cubic  millimetre  (about  o^th 
of  an  inch)  of  human  blood  there  are  5,000,000  red  cor- 
puscles, having  a  surface  of  643  millimetres. 

After  a  variable  time  from  their  removal  from  the  ves- 
sels they  suffer  contraction,  and  assume  a  stellate,  or 
mulberry  form  (Plate  XVIII,  Fig.  139).  This  occurs 
more  rapidly  in  feverish  states  of  the  system.  On  the 
warm  stage  they  suffer  still  greater  alterations.  Inden- 
tations appear,  which  cause  bea.d-like  projections,  some 
of  which  become  fragments,  having  molecular  motion 
(Plate  XVIII,  Fig.  139).  The  substance  of  red  corpuscles 
is  elastic  and  extensible,  and  may  be  seen  in  the  vessels  to 
elongate  and  curve  so  as  to  adapt  themselves  to  the  calibre 
of  the  vessels. 

Electric  discharges  through  the  red  corpuscles  produce 
various  changes  of  form.  Alkalies  dissolve,  and  acids 


188  THE    M1CROSCOPIST. 

cause  a  precipitate  in  them.  They  are  tinged  by  neutral 
solutions  of  carmiuate  of  ammonia.  One-half  to  1  per 
cent,  of  salt  added  to  the  staining  fluid  causes  the  nuclei 
only  of  Amphibian  corpuscles  to  be  stained.  Chloroform, 
tannin,  and  other  reagents,  produce  various  changes, 
which  suggest  a  wide  field  of  research  connected  with 
Therapeutics. 

The  old  opinion  of  the  structure  of  red  corpuscles  rep- 
resented them  as  vesicles  consisting  of  a  membrane  and  its 
contents,  but  Max  Schultze,  in  1861,  showed  that  a  mem- 
brane was  not  constant.  This  may  be  verified  by  break- 
ing them  under  pressure. 

Briicke's  experiment  on  the  astringent  action  of  boracic 
acid  on  the  blood  of  Triton,  repeated  by  Strieker  and  Lan- 
kester,  shows  the  red  corpuscles  to  possess  a  double  struc- 
ture. There  is  a  body,  called  (Ecoid ;  a  porous,  non-con- 
tractile, soft,  transparent  mass ;  and  a  retractile  substance, 
or  Zooid,  containing  the  heemoglobulin,  which  fills  the  in- 
terspaces of  the  CEcoid.  The  Zooid  seems  identical  with 
simple  cell-substance,  or  bioplasm. 

3.  Colorless,  or  White  Corpuscles. — These  appear  to  be 
simply  masses  of  bioplasm  of  various  sizes.  Some  are 
quite  small,  and  many  are  larger  than  the  red  corpuscles. 
Their  number  is  much  smaller  than  the  red  disks,  being 
about  1  to  350,  or  even  less.  In  leucaemia  and  other  dis- 
eases their  relative  number  is  much  greater.  In  the  blood 
of  cold-blooded  animals,  and  in  that  of  vertebrata,  if  the 
normal  temperature  is  continued  by  means  of  a  warm 
stage,  the  amoeboid  motions  are  quite  perceptible  with  a 
high  magnifying  power  (Plate  XVIII,  Fig.  139).  They 
may  also  be  seen  to  take  up  small  particles  of  matter  into 
their  interior,  such  as  cinnabar,  carmine,  milk-globules, 
and  even  portions  of  the  red  globules. 

Both  red  and  white  cells  are  forced  through  the  unin- 
jured walls  of  small  vessels  by  impeded  circulation,  but 
the  white  cells  thus  migrate,  by  virtue  of  their  vital  con- 


PLATE   XVIII, 


FIG.  137. 


Capillary  circulation  in  a  portion  of  the  web  of  a  Frog's  foot. 
FIG.  138.  FIG.  139 


Alterations  in  form  in  blood-discs : — 1,  Stellate  or  mul- 
berry form;  2,  On  warm  stage;  3,  Amoeboid  white-cell 
forms. 

FIG.  140. 


Blood-discs : — 1,  Eliptic  Discs  of  Amphibia ; 
2,  Human  red-corpuscles ;  3,White  or  lymph- 
corpuscle;  4,  Rouleaux  of  red-discs. 


FIG.  141. 


Pus-corpuscles: — o,  with  acetic  acid. 
FIG.  142. 


Mucous  corpuscles  and  epithelium. 


Varieties  of  Epithelium  ; — a,  Tessalated ;  6,  Squamous; 
c,  Glandular;  d,  Columnar ;  e,  Ciliated. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          189 

tractility,  in  the  healthy  body,  and  in  greater  numbers  in 
diseased  states  ;  in  some  cases  re-entering  the  lymphatic 
circulation,  and  in  others  penetrating  into  various  tissues. 
The  pus-corpuscles  appearing  in  the  vicinity  of  inflamed 
parts  are  shown  by  this  discovery,  made  by  Waller  and 
Cohnheim,  to  be  nothing  but  migratory  lymphoid  or 
white  cells  of  the  blood.  The  change  of  form  and  place 
of  these  amoeboid  cells  is  readily  seen  by  placing  a  drop  of 
frog's  blood  on  a  glass  cover,  and  inverting  it  over  a  moist 
cell.  As  it  coagulates,  a  zone  of  serum  extends  round  the 
clot,  in  which  the  migrated  cells  will  be  found. 

The  colorless  cells  originate  in  the  chyle  and  lymph- 
systems,  although  some  may  come  from  the  spleen  and 
the  medulla  of  bones,  multiplying  in  the  blood  itself,  and 
they  pass  into  red  corpuscles.  Transitional  forms  have 
been  found  in  the  general  mass  of  blood,  in  the  spleen,  and 
in  the  marrow  of  bones. 

The  white  or  colorless  cells  of  blood  are  identical  writh 
the  cells  of  chyle,  lymph,  pus,  mucus,  and  saliva.  They 
are  often  described  under  the  term  leucocytes  (white  cells.) 

The  leucocytes  of  saliva  (salivary  corpuscles)  and  of  pus 
contain  granules  or  globules  of  formed  material,  which 
exhibit  for  some  time  a  peculiar  dancing  movement  (see 
page  120). 

When  at  rest,  or  in  a  lifeless  condition,  the  white  cells 
are  of  spheroidal  form,  and  generally  exhibit  granules  and 
globules  of  fat.  Acetic  acid  develops  a  nucleus,  and  some- 
times splits  it  into  several  (Plate  XVIII,  Fig.  140). 

II.  Lymph  and  Chyle. 

The  vessels  of  the  lymphatic  or  absorbent  system  re- 
ceive the  liquid  part  of  the  blood  which  has  passed  from 
the  capillaries,  together  with  the  products  of  decomposi- 
tion in  the  tissues,  and  return  them  to  the  circulation. 
The  lymphatics  of  the  intestinal  canal  receive  during 


190  THE    MICROSCOPIST. 

digestion  a  mixture  of  albuminous  and  fatty  matters, 
which  is  known  as  chyle,  and  these  vessels  have  obtained 
the  name  of  lacteals.  The  cells  in  this  fluid  are  leucocytes, 
identical  with  white  cells  in  blood.  They  originate  in  the 
lymphatic  glands  and  "Peyer's  patches"  of  the  intestine, 
and  are  the  corpuscles  of  these  organs  which  have  been 
carried  off  by  the  fluid  stream. 

III.  Mucus. 

Is  a  tenacious  semifluid  substance  which  covers  the 
surface  of  mucous  membranes.  It  contains  cast-off  epi- 
thelial and  gland-cells,  and  the  mucus  corpuscle,  which,  as 
we  have  before  said,  is  identical  with  other  leucocytes. 
Synovial  fluid  is  of  similar  nature.  It  is  now  regarded  as 
a  transformation  product  of  the  epithelial  cells,  and  not 
to  originate  as  a  secretion  from  special  glands  (Plate 
XVIII,  Fig.  141). 

2.  EPITHELIUM  AND  ITS  APPENDAGES. 

Epithelium  (from  e-i,  upon,  and  Oattw,  to  sprout)  is  so 
called  since  it  was  formerly  supposed  to  sprout  from  mem- 
brane. It  is  a  tissue  formed  of  cells  more  or  less  closely 
associated,  which  is  found  in  layers  upon  external  and 
internal  surfaces.  The  cells  are  generally  transparent, 
with  vesicular,  homogeneous,  or  granular  nuclei,  the  lat- 
ter being  the  remains  of  the  original  leucocyte  or  bio- 
plast. In  the  older  cells  the  nucleus  is  absent,  the  entire 
mass  having  been  transformed. 

The  forms  of  epithelial  cells  vary  according  to  situation 
or  function.  The  original  form  is  spheroidal,  but  changes 
by  compression,  etc. 

1.  Tessellated  or  pavement  epithelium  (Plate  XVIII, 
a,  Fig.  142).  These  are  cells  whose  formed  material  is 
flattened,  and  which  are  united  at  their  edges.  They  are 
sometimes  hexagonal,  and  often  polyhedral,  in  form. 

Examples :  Serous  and  synovial  membranes ;  the  pos- 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          191 

terior  layer  of  the  cornea ;  the  peritoneal  surface ;  the 
interior  of  bloodvessels,  and  shut  sacs  generally. 

2.  Squamous  or  scaly  epithelium.     The  cells  are  flat, 
and  overlap  each  other  at  the  edges  (Plate  XVIII,  6,  Fig. 
142). 

Examples :  Epidermis ;  many  parts  of  mucous  mem- 
branes, as  the  mouth,  fundus  of  bladder,  vagina,  etc. 

3.  Glandular   epithelium  (Plate   XVIII,  c,  Fig.   142). 
The  cells  are  round  or  oval  bioplasts,  often  polyhedral 
from  pressure,  and  the  formed  material  is  often  soft. 

Examples :  Liver  cells,  convoluted  tubes  of  kidney,  and 
interior  of  glands  generally. 

4.  Columnar  epithelium  (Plate  XVIII,  d,  Fig.  142). 
Cells  cylindrical  or  oblong,  arranged  side  by  side.     A 
bird's-eye  view  shows  them  similar  to  the  tessellated  form, 
hence  they  should  be  seen  from  the  side. 

Examples :  Villi  and  follicles  of  intestine,  ducts  of 
glands,  urethra,  etc. 

Some  of  the  columnar  or  cylinder-cells  have  a  thickened 
border  or  lid  perforated  with  minute  pores  (Plate  XVIII, 
/,  Fig.  142).  They  are  found  in  the  small  intestine,  gall- 
bladder, and  biliary  ducts. 

5.  Ciliated    epithelium   (Plate    XVIII,   e,   Fig.    142). 
These  are  cylindrical  cells  having  vibratile  cilia,  whose 
motions  produce  a  current  in  the  surrounding  fluid. 

Examples:  The  upper  and  back  nasal  passages,  the 
pharynx,  bronchi,  Fallopian  tubes,  etc. 

The  Hair. — Hairs  are  filiform  appendages,  composed  of 
a  modified  epithelial  tissue  of  rather  complex  structure. 
They  originate  in  a  follicle,  which  is  a  folding  in  of  the 
skin.  The  shaft  of  the  hair  is  the  portion  projecting 
above  the  skin,  and  the  root  is  concealed  in  the  hair-fol- 
licle. The  bulb  of  the  root  is  the  rounded  terminal  part, 
which  is  hollow  below,  and  rests  on  a  papilla  which  rises 
from  the  floor  of  the  follicle  (Plate  XIX,  Fig.  143).  Be- 
tween the  follicle  and  hair  is  a  sheath,  W7hich  is  divided 


192  THE    MICROSCOPIST. 

into  an  external  and  internal  portion.  The  cells  of  the 
hair  may  be  isolated  by  sulphuric  acid  or  solution  of  soda. 
They  overlap  each  other  like  tiles,  so  as  to  present  undu- 
lating or  jagged  lines  across  the  surface  of  a  fresh  hair. 
The  felting  property  of  wool  depends  on  the  looseness  of 
this  overlapping.  Air-bubbles  are  often  found  in  hair, 
especially  in  the  medullary  or  axial  portion,  and  give  a 
silvery  appearance  to  white  hair.  The  granules  of  pig- 
ment are  generally  found  in  the  cortical  portion. 

Nails  are  nothing  more  than  modified  cuticle,  depen- 
dent for  their  growth  on  the  vessels  of  the  matrix  or  bed 
of  the  nail.  Their  epithelial  cells  may  be  demonstrated 
by  soaking  in  caustic  soda  or  potash. 

Corns,  warts,  and  horn  have  similar  origin. 

Enamel  of  the  Teeth. — The  minute  structure  of  dental 
tissue  will  be  described  hereafter,  but  as  the  enamel  is 
generally  considered  to  be  of  epithelial  origin,  some  ac- 
count of  it  belongs  here. 

CD 

The  edge  of  the  jaw  is  first  marked  by  a  slight  groove, 
known  as  the  dental  groove,  and  is  covered  with  a  thick 
ridge  of  epithelium,  called  the  dental  ridge  (Plate  XIX, 
Fig.  144,  1  a,  2  a}.  The  epithelium  grows  down  in  a 
process  which  has  been  called  the  enamel  germ  (1  d}. 
This  becomes  doubled  by  the  upward  growth  of  the 
dental  germ  (2,  3,/),  which  originates  from  connective 
tissue.  The  epithelial  cells  become  transformed  into 
enamel  columns  or  prisms. 

3.  CONNECTIVE  SUBSTANCES  OR  TISSUES. 

The  term  connective  tissue  has  been  given  to  a  variety 
of  structures  which  probably  start  from  the  same  rudi- 
ments, and  have  a  near  connection  with  each  other.  It 
is  unfortunate  that  a  name  descriptive  of  function  should 
be  applied  to  structure,  yet  the  present  state  of  histology 
requires  an  account  of  substances  thus  called. 

Connective  tissues  are  all  those  which  may  be  regarded 


PLATE  XIX. 


FIG.  144.  a. 


Structure  of  Human  Hair. 

FIG.  145. 


Connective-tissue  elements.  From  the  Frog's  Thigh  :— 
a,  contracted  cell;  ft,  ramified  ;  c,  d,  motionless  gran- 
ular cells;  /,  fibrilise;  g,  connective-tissue  bundle; 
«,  elastic  fibre  net-work. 


Development  of  the  enamel:— a,  dental  ridge; 
6,  young  layer  of  epithelium;  c,  deep  layer;  dt 
enamel  germ  ;  e,  enamel  organ  ;  /,  dental  germ. 


FIG.  146. 


White  Fibrous  Tissue,  from  Ligament. 


FIG.  147. 


Yellow  Fibrous  Tissue,  from  Ligamentum  Nuchse 
of  Calf. 


FIG.  148. 


Fatty  Tissue. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          193 

as  basement-membranes,  supporting  layers  or  investments 
for  epithelial  structures,  blood,  lymph,  muscle,  and  nerves. 
It  includes  ordinary  connective  tissue  (white  and  yellow 
fibrous  tissues),  cartilage,  bone,  corneal  tissue,  dentine, 
and  fatty  tissue. 

Most  of  the  difficulty  found  in  the  consideration  of 
these  tissues  arises  from  discussions  relative  to  the  inter- 
cellular substance.  Max  Schultze  and  Beale  agree  in  re^ 
garding  it  to  originate  from  the  protoplasm  or  bioplasm 
of  cells. 

The  cells  are,  according  to  Frey,  originally  spheroidal, 
with  vesicular  nuclei,  and  between  them  is  an  albuminous 
intercellular  substance — a  product  of  the  cells,  or  trans- 
formed cells— which  usually  undergoes  fibrillation,  while 
the  cells  become  stunted,  or  develop  into  spindle-shaped' 
or  stellate  elements.  Calcification  of  the  intercellular  sub- 
stance occurs  in  some  of  these  tissues,  as  bone  and  dentine. 

The  cells  of  connective  tissue  present  many  varieties, 
Recklinghausen  first  observed  migrating  lymphoid  cells 
or  bioplasts  in  the  cornea  of  the  eye,  the  tail  of  the  tad- 
pole, the  peritoneum,  and  in  various  other  places.  The 
exit  of  white  corpuscles  from  the  vascular  walls  renders 
it  probable  that  these  amoeboid  cells  originate  in  the  blood. 
Granular  cells,  of  various  forms — rounded,  fusiform,  and 
stellate — are  also  observed.  Some  of  the  stellate  cells 
give  off  anastomosing  branches.  Pigment  cells,  filled  with 
granular  pigment,  are  also  met  with  (Plate  XIX,  Fig. 
145). 

In  its  earliest  stages,  connective  tissue  consists  of  closely- 
compressed  cells,  but  in  the  adult  two  principal  forms 
have  been  distinguished ;  first,  those  networks  and  trabec- 
ulfe,  developed  from  cells,  which  do  not  yield  gelatin  on 
boiling,  and,  secondly,  fibrillar  connective  tissue  composed 
of  a  gelatin-yielding  substance.  Of  the  first  kind  we  notice 
the  following  varieties : 

1.  Independent  masses  of  gelatinous  or  mucous  tissue, 

13 


194  THE    MICROSCOPIST. 

consisting  of  nucleated  cells,  giving  off  smooth  anasto- 
mosing trabeculee,  as  in  the  early  stage  of  the  vitreous 
humor  of  the  eye  and  of  the  gelatinous  tissue  of  the  um- 
bilical cord,  etc. 

2.  Very  delicate  reticular  tissue  found  in  the  eye  and  in 
the  interior  of  nerve-centres. 

3.  A  network  filled   with  lymphoid  cells  (adenoid  or 
cytogenous  tissue)  in  the  glands  of  the  lymphatic  system, 
and  around  the  fasciculi  of  fihrillar  connective  tissue. 

4.  A  coarser  network  in  the  ligamentum  pectinatum 
of  the  human  eye. 

5.  A  tissue  formed  of  fusiform  and  stellate  cells,  as  in 
the  interior  of  the  kidneys 

The  second  form  referred  to,  or  the  fibrillar  connective 
tissue,  was  the  only  form  to  which  the  term  connective 
tissue  was  formerly  applied.  It  is  composed  of  gelatin- 
yielding  fibrillse,  which  may  be  split  into  skein-like  por- 
tions of  various  breadth.  (Plate  XIX,  Fig.  146.)  Per- 
manganate of  potash  stains  it  brown.  Acetic  and  dilute 
mineral  acids  cause  the  tissue  to  swell  so  that  the  appear- 
ance of  fibrillation  is  lost  through  compression,  and  the 
cells,  or  nuclei,  are  made  manifest.  Chloride  of  gold 
staining  exhibits  both  fibrillre  and  cells. 

Elastic  fibres  (yellow  elastic)  (Plate  XIX,  Fig.  147)  are 
apparent  in  all  forms  of  connective  tissue  which  have  been 
made  transparent  by  boiling,  or  acetic  acid.  They  are 
non-gelatinizing,  cylindric,  slightly  branched,  or  forming 
plexuses.  In  some  fasciculi  of  fibrillar  connective  tissue,  as 
seen  after  the  action  of  acetic  acid,  elastic  fibres  appear  in 
hoops,  or  spirals,  around  them.  In  the  ligamentum  nu- 
cleae  of  the  giraffe  the  elastic  fibres  are  marked  by  trans- 
verse striae,  or  cracks.  Elastic  fibres  often  form  flattened 
trabeculae,  or  are  fused  into  elastic  plates,  or  membranes, 
with  foraminae.  as  in  arterial  tunics. 

The  ligaments  of  the  skeleton,  the  periosteum,  peri- 
chondrium,  aponeuroses,  fasciae,  tendons,  and  generally  all 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.  195 

the  tunics  of  the  body,  afford  examples  of  the  fibrillar 
connective  tissue. 

Fatty  Tissue. — The  loose  connective  tissue  contains  in 
various  parts  great  numbers  of  cells  filled  with  fat.  Their 
form  is  round,  or  oval,  and  are  often  divided  into  groups, 
or  lobules,  by  trabeculse.  (Plate  XIX,  Fig.  148.)  Each 
lobule  has  its  own  system  of  bloodvessels,  which  divide 
into  such  numerous  capillaries  that  the  smaller  groups, 
and  even  individual  fat-cells,  are  surrounded  by  vascular 
loops.  Sometimes  the  contents  of  the  cells  appear  in* 
needle-shaped  crystals,  often  collected  in  a  brush-like  form. 
Fat-cells  seem  to  be  chiefly  receptacles  for  the  deposit  of 
superabundant  oleaginous  nutriment,  and  are  analogous 
to  the  starch-cells  in  vegetables. 

Cartilage. — This  is  formed  of  cells  in  an  originally  homo- 
geneous intercellular  substance.  The  only  difference  be- 
tween what  was  formerly  distinguished  as  cartilage  and 
fibre-cartilage  is  that  the  matrix  or  intercellular  substance 
of  the  latter  is  fibrous. 

The  cells,  or  cartilage-corpuscles,  are  nucleated,  and  lie 
in  cavities  of  various  sizes  and  form  in  the  matrix  (Plate 
XX,  Fig.  149).  Two  nuclei  often  appear  in  one  cell.  It 
is  yet  a  question  whether  the  capsule  and  matrix  are  the 
secretion  of  the  cells  which  has  become  solid,  or  a  part  of 
the  body  of  the  cell  which  has  undergone  metamorphosis. 

The  multiplication  of  cartilage-cells  is  endogenous.  By 
segmentation,  two,  four,  or  a  whole  generation  of  daughter- 
cells,  so  called,  may  lie  in  the  interior  of  a  capsule.  In  this 
way  growing  cartilage  may  acquire  a  great  number  of 
elements. 

In  the  ear  of  the  mouse,  etc.,  wre  observe  a  form  of  car- 
tilage which  is  wholly  cellular,  and  possesses  no  matrix 
(Plate  XX,  Fig.  150). 

Bone,  or  osseous  tissue,  is  formed  secondarily  from  meta- 
morphosed descendants  of  cartilage  or  connective-tissue 
cells,  and  is  the  most  complex  structure  of  this  group.  It 


196  THE    MICROSCOPIST. 

consists  essentially  of  stellate  ramifying  spaces  containing 
cells,  and  a  hard,  solid,  intermediate  substance.  The  latter 
is  composed  of  glutinous  material  rendered  hard  by  a  mix- 
ture of  inorganic  salts,  chiefly  of  calcium. 

As  all  bones  are  moulded  first  in  cartilage  it  was  natural 
to  conceive  that  they  were  developed  by  a  transformation 
of  cartilage.  Much  variety  of  opinion  still  exists  respect- 
ing the  process,  but  it  is  generally  conceded  that  although 
cartilage  may  undergo  calcification,  true  bone  is  not  formed 
until  the  cartilage  is  dissolved.  New  generations  of  stel- 
late cells  appear  in  a  matrix,  which  is  first  soft  and  then 
calcified.  New  bone  may  also  grow  from  the  periosteum 
by  means  of  a  stratum  of  cells  called  osteoblasts.  The  de- 
tails of  the  process  are  too  extensive  for  a  treatise  like  the 
present.  If  sections  of  growing  bone  are  decalcified  with 
chromic  acid  and  treated  with  carmine,  the  osteoblastic 
layers  and  adjacent  youngest  bony  layer  acquire  an  in- 
tensely red  color,  while  the  rest  of  the  tissue,  except  the 
bone-corpuscles,  remains  uncolored. 

Fine  sections  cut  from  a  long  bone  longitudinally  and 
transversely  will  show  the  microscopic  structure,  consist- 
ing of  the  Haver  sian  canals  (Plate  XX,  Fig.  151,  a]  sur- 
rounded with  concentric  lamellae  of  compact  structure  (6,  b). 
There  are  also  intermediate  and  periosteal  lamellae  (c,  d). 
The  cavities  containing  the  bone-cells,  or  bioplasts  (e,  e,) 
are  of  various  sizes,  from  0.0181  to  0.0514  millimetres 
long,  and  from  these  lacunce  run  the  canaliculi  in  an  irregu- 
lar radiating  course  (/,/)•  In  a  balsam-mounted  specimen 
these  hollows  sometimes  retain  air,  by  which  the  structure 
is  rendered  more  apparent. 

Dentine  is  the  structure  of  which  the  teeth  are  most 
largely  composed.  It  consists  of  minute  tubes  filled  with 
bioplasm,  which  radiate  from  the  central  cavity  of  the 
tooth,  the  interspaces  between  the  tubes  being  solidified 
by  earthy  salts  so  that  the  tissue  is  harder  than  bone. 

Histologically  a  tooth  may  be  said  to  be  made  of  three 


PLATE 


FIG.  149. 


'O 


FIG.  150. 


Cellular  Cartilage  of  Mouse's  Ear. 


Section  of  the  Branchial  Cartilage  of  Tadpole. 


^~^<£ 


Longitudinal  and  transverse  section  of  Bone: — a,  Haver- 
sian  canals;  6,  concentric  lamellae;  c,  intermediate;  d, 
periostial  lamellae;  e,  bone-cells;  /,  canaliculi. 


FIG. 152. 


J?      ".•,"'.;  \> 


Striated  Muscular-fibre,  separated  into  fibrillie 


Vertical  section  of  Human 
Molar  Tooth:— 1,  enamel;  2, 
cementumorcrustapetrosa  ; 
3, dentine,  or  ivory;  4, osse- 
ous excrescence,arising  from 
hypertrophy  of  cementum  ; 
5,  pulp-cavity;  6,  osseous 
lacunae  at  outer  part  of  den- 
tine-  Involuntary  Muscular-fibre 


Sarcolemma. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          197 

kinds  of  tissue:  the  cement,  a  bony  substance,  coating  the 
root  of  the  tooth,  containing  bone-cells  and  canaliculi,but 
no  Haversian  canals,  the  pulp  in  the  central  cavity  of  the 
tooth  serving  for  the  nutrition  of  the  organ,  as  a  large 
Haversian  canal ;  the  dentine,  or  ivory,  constructed  as 
above  described;  and  the  enamel, covering  the  crown, arid 
consisting  of  columns  or  prisms,  often  hexagonal,  which 
are  the  hardest  and  densest  structures  of  the  body  (Plate 
XX,  Fig.  152). 

The  development  of  enamel  from  epithelium  has  been 
referred  to  on  page  192.  The  dental  germ  corresponds  to 
a  papilla  of  the  mucous  membrane,  and  in  an  early  stage 
is  covered  by  delicate  stratified  cells — the  dentine  cells, 
or  odontoblasts — which  produce  dentine.  Teeth  are  thus 
produced  abnormally  in  other  situations  besides  the  jaws, 
as  in  ovarian  cysts,  etc. 

Before  the  development  of  the  'first,  or  milk  teeth,  the 
rudiments  of  the  permanent  teeth  exist  as  a  fold  or  leaf 
of  epithelium  springing  from  the  enamel  germ. 

II.  COMPOUND  TISSUES. 

1.  Muscle. — This  is  the  tissue  by  which  the  principal 
movements  of  the  body  are  performed.  It  consists  of 
fibrin,  which  is  endowed  with  special  contractile  power. 
It  is  of  two  kinds,  the  voluntary,  pertaining  to  organs  of 
voluntary  motion,  and  the  involuntary,  found  in  situa- 
tions which  are  not  under  the  control  of  volition,  as  the 
coats  of  bloodvessels,  alimentary  canal,  uterus,  and  blad- 
der. The  fibres  of  voluntary  muscles  are  marked  with 
transverse  striae.  Involuntary  muscular  fibres  are  smooth, 
except  in  a  few  instances,  as  the  fibres  of  the  heart  and 
some  of  those  in  the  oesophagus,  which  are  striated. 

The  fibres  are  connected  with  and  invested  by  connec- 
tive tissue,  and  arranged  in  parallel  sets,  with  vessels  and 
nerves  in  the  intervals,  and  are  attached  to  the  parts  they 


198  THE    MICROSCOPIST. 

are  designed  to  move  by  tendon,  aponeuroses,  or  some  form 
of  fibrous  tissue.  The  organs  or  muscles  thus  formed  are 
generally  solid  and  elongated,  but  sometimes  expanded. 

Involuntary  or  unstriped  muscular  fibres  are  flat  bands 
or  spindle-shaped  fibres  with  nuclei,  which  may  be  re- 
garded as  the  remains  of  the  formative  bioplasm  (Plate 
XX,  Fig.  153).  They  are  usually  transverse,  or  interlace 
with  each  other  on  the  walls  of  cavities  and  vessels.  In 
the  heart  the  fibres,  though  involuntary,  are  striped  and 
branching.  Striped  fibre  varies  from  g'0th  to  ^o^th  inch 
in  diameter.  It  is  largest  in  insects,  in  which  individual 
fibrils  may  be  readily  obtained,  especially  from  the  thoracic 
muscles.  They  are  generally  found  in  bundles  of  fibrils, 
splitting  longitudinally  or  in  disks,  and  each  bundle  is 
inclosed  in  a  sheath  or  sarcolemma  (Plate  XX,  Fig.  154). 

The  transverse  striation  of  muscle  is  subject  to  much 
variation,  and  the  precise  nature  of  the  sarcous  elements 
which  produce  the  appearance  is  yet  a  matter  of  dispute, 
but  in  all  probability  the  ultimate  elements  are  sarcous 
prisms  or  particles  imbedded  in  a  homogeneous  mass,  and 
by  their  mutual  attraction,  excited  by  various  stimuli, 
the  contraction  of  the  fibre  takes  place. 

For  the  purpose  of  observation,  the  connective  tissue 
may  be  removed  from  muscular  fibre  by  gelatinizing  it 
with  dilute  sulphuric  acid,  and  dissolving  it  at  a  temper- 
ature of  104°  F.  The  nuclei  of  muscular  fibre  are  seen 
after  treating  with  acetic  acid,  and  may  be  stained  with 
carmine  fluid,  etc. 

2.  Nerve-tissue. — The  term  nerve  was  applied  by  the 
ancients  to  tense  cords,  as  bow-strings,  musical  strings, 
etc.,  and  was  appropriated  to  the  fibres  now  called  nerves, 
because  they  deemed  them  to  operate  by  tremors,  vibra- 
tions, or  oscillations,  another  instance  of  wrong  naming 
of  structure  from  an  opinion  respecting  function.  Hip- 
pocrates, Galen,  and  others,  however,  thought  nerves  were 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          199 

hollow  tubes,  conveying  fine  ethereal  fluids,  termed  ani- 
mal spirits. 

Nervous  matter  is  soft,  unctuous,  and  easily  disturbed, 
hence  it  is  necessary  to  examine  it  while  fresh.  Histo- 
logically  it  is  divided  into  fibres  and  cells,  imbedded  in 
connective  tissue. 

Nerve-fibres  are  of  two  kinds,  the  medullated,  or  dark- 
bordered  threads,  and  the  pale,  or  non-medullated.  Med- 
ullated fibres  consist  of  a  delicate  envelope  of  connective 
tissue,  called  the  neurilemma  or  primitive  sheath,  an  axis- 
cylinder  or  albuminous  portion,  extending  down  the  cen- 
tre, and  a  portion  composed  of  a  mixture  of  albumen, 
cerebral  matter,  and  fat,  surrounding  the  axis-cylinder 
(Plate  XXI,  Fig.  155,  A,  B,  c).  This  latter  is  the  medul- 
lary sheath,  or  white  substance  of  Schwann.  It  changes 
rapidly,  so  as  to  coagulate  and  become  granular.  Alka- 
lies render  it  fluid,  so  as  to  exude  in  fat-like  drops.  Ab- 
solute alcohol,  chromate  of  potass  and  collodion,  contract 
the  sheath,  so  as  to  permit  the  axis-cylinder,  which  is  the 
essential  part  of  the  nerve,  to  protrude  (Plate  XXI,  E, 
Fig.  155).  Anilin,  carmine,  nitrate  of  silver,  and  chloride 
of  gold  stain  the  axis,  while  osmic  acid  blackens  only  the 
medullary  sheath. 

Non-medullary  or  pale  nerve-fibres  are  regarded  as  em- 
bryonic or  developmental  forms  (Plate  XXI,  D,  Fig.  155). 
The  ganglionic  fibres  of  the  sympathetic  (Remak's  fibres) 
are  flat,  homogeneous  bands,  with  round  or  oval  nuclei. 
Some  have  considered  them  as  formed  of  connective  tis- 
sue, but  their  nervous  character  is  generally  conceded. 

Schultze  and  others  regard  the  axis-cylinder  as  made  up 
of  extremely  delicate  fibrillee. 

.  Nerve-cells,  or  ganglion  corpuscles,  are  of  two  kinds, 
those  without  and  those  with  processes.  The  first  are 
called  apolar,  and  the  latter  unipolar,  bipolar,  or  multi- 
polar,  according  to  the  number  of  ramifications.  The 
cells  are  nucleated,  and  inside  the  nucleus  is  usually 


200  THE    MICROSCOPIST. 

another,  the  nucleolus.  Dr.  Beale  discovered  certain  gan- 
glion-cells in  the  sympathetic  of  the  tree-frog  (in  the  au- 
ricular septum  of  the  heart),  one  of  whose  poles  is  encir- 
cled spirally  by  the  others  (Plate  XXI,  Fig.  156). 
'  The  ultimate  structure  of  ganglia  or  nervous  knots, 
and  the  relation  of  the  fibres  to  the  cells,  opens  a  wide 
field  of  research.  In  the  muscle  of  the  heart,  etc.,  many 
of  these  ganglia  seem  to  form  special  nervous  systems. 
Dr.  Beale  has  described  the  nerves  ramifying  on  the  capil- 
laries and  involuntary  muscular  fibrils  of  the  terminal  ar- 
teries as  a  self-regulating  mechanism  for  the  distribution 
of  blood  (Plate  XXI,  Fig.  157).  Thus,  if  a  tissue  receives 
excess  of  pabulum,  the  capillary  nerve-fibre  is  disturbed 
and  transmits  a  change  to  the  ganglion,  and  thence 
through  the  efferent  nerve  to  the  muscular  fibres  of  the 
artery,  and  vice  versa. 

Meissner  has  shown  many  ganglionic  plexuses  in  the 
submucous  coat  of  the  alimentary  canal.  Another  system 
of  the  same  kind,  called  the  plexus  myeniericus,  was  dis- 
covered by  Auerbach  between  the  muscular  layers  of  the 
intestinal  tube.  Similar  plexuses  exist  in  other  organs. 

As  to  the  peripheral  termination  of  nerve-fibres,  there 
is  still  considerable  discussion.  Most  of  the  German  his- 
tologists  consider  the  nerves  of  voluntary  muscles  to  ter- 
minate in  end  plates,  in  which  the  neurilemma  becomes 
continuous  with  the  sarcolemma  of  the  muscular  fibre. 
Dr.  Beale  maintains  that  there  is  a  plexus  of  minute  nerves 
over  the  fibrils.  In  some  of  my  own  preparations,  espe- 
cially some  stained  with  soluble  Prussian  blue,  a  disk 
formed  of  a  plexus  of  excessively  minute  nerve-fibres  is 
observed,  from  which  tortuous  branches  go  to  other  mus- 
cle-fibres. 

In  the  cornea,  Cohnheim  and  Klein  have  traced  fine 
nerve-fibres  to  the  epithelial  cells  of  the  conjunctiva,  by 
means  of  chloride  of  gold  staining. 

3.  Glandular  tissue  consists  of  a  fine  transparent  mem- 


PLATE  XXI. 


FIG. 155. 


FIG.  156. 


\ 


Various  Ganglionic  Nerve-cells. 


FIG.  157 


Nerve-fibres. 


Self-regulating  System  of  Ganglia — nerves, 
arteries,  and  capillaries. 


Glandular  Tissue. 


FIG.  160. 


Layers  of  Blastoderm. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.  201 

brane,  through  which  the  plasma  transudes,  and  cells  of 
glandular  epithelium.  A  vascular  network  exists  on  the 
surface  of  the  membrane,  from  which  the  material  of  the 
secretion  is  obtained.  This  membrane  may  be  a  simple 
follicle,  or  tube,  as  in  the  mucous  membrane,  or  system  of 
tubes,  as  in  the  kidneys,  a  convoluted  tube,  a  simple  open 
vesicle,  a  racemose  aggregation  of  vesicles,  or  a  close  cap- 
sule which  discharges  itself  by  bursting.  (Plate  XXI, 
Fig.  158). 

4.  Vascular  Tissue. — The  smallest  bloodvessels  and  lym- 
phatics, called  capillaries,  are  minute  tubes,  consisting  of  a 
series  of  flattened  epithelial  cells,  and  containing  stomata, 
or  openings  through  which  white  or  red  blood-corpuscles 
may  occasionally  pass  (Plate  XX,  Fig.  159,  a,  b).  The 
larger  trunks  have,  in  addition  to  the  cellular  layer,  one 
of  longitudinally  striated  connective  tissue,  a  middle  coat 
containing  transverse  muscular  fibres,  and  an  external  coat 
of  connective  tissue  (Plate  XXI,  Fig.  159).  The  distribu- 
tion of  the  capillary  bloodvessels  is  various,  according  to 
the  nature  or  function  of  the  organ  or  tissue  in  which  they 
are  found. 

DEVELOPMENT  OF  THE  TISSUES. 

It  has  been  stated,  page  125,  that  reproduction  in  the 
higher  animals  consists  of  an  ovum  fecundated  by  contact 
with  a  sperm-cell,  or  spermatozoid.  The  ovum  consists 
of  a  germinal  vesicle,  containing  one  or  more  germinal  spots, 
and  included  within  a  vitellus  (a  yelk)  which  is  surrounded 
by  bvitelline  membrane,  which  may  have  additional  invest- 
ments in  the  form  of  layers  of  albumen  and  of  an  outer 
coriaceous  or  calcified  shell. 

The  first  step  in  the  development  of  the  embryo  is  the 
division  of  the  vitelline  substance  into  cleavage-masses,  at 
first  two,  then  four,  then  eight,  etc.  This  process  of  yelk- 
division  may  affect  the  whole  yelk  or  a  part  of  it,  and  re- 
sults in  the  formation  of  a  blastoderm,  or  embryogenic 


202  THE    MICROSCOPIST. 

tissue.  This  rudimentary  embryonic  tissue  consists  of 
three  layers  of  cells,  or  germinal  plates.  The  upper  is  the 
corneous  layer,  or  epiblast,  the  middle  one  the  intermediate 
plate,  or  mesoblast,  and  the  lower  the  intestinal  glandular 
layer,  or  hypoblast  (Plate  XXI,  Fig.  160).  From  these 
the  various  tissues  and  organs  are  developed. 

The  outer  plate  produces  the  epithelium  of  the  skin  and 
its  appendages,  with  the  cellular  elements  of  the  glands  of 
the  skin,  mammae,  and  lachrymal  organs.  By  a  peculiar 
folding  over  the  axis  this  plate  also  produces  the  elements 
of  the  brain  and  spinal  cord,  and  the  internal  parts  of  the 
organs  of  special  sense.  The  physiological  significance  of 
this  layer  is,  therefore,  very  great. 

The  lower  stratum  of  the  blastoderm  supplies  the  epi- 
thelium of  the  digestive  tract,  and  the  cellular  constituents 
of  its  various  glands,  together  with  the  liver,  lungs,  and 
pancreas. 

The  middle  layer  supplies  the  material  for  many  struc- 
tures. The  whole  group  of  connective  substances,  or 
tissues  of  support;  muscular  tissue;  blood  and  lymph, 
with  their  containing  vessels  ;  lymph-glands,  including 
the  spleen,  etc.,  all  arise  from  this.  The  epithelial  cells 
of  such  tubes  and  cavities  as  originate  in  this  layer  are 
regarded  as  different  from  those  of  true  glands,  and  are 
more  permeable  to  fluids.  They  have  been  termed  false 
epithelium,  or  endothelium. 

The  following  description,  by  Professor  Huxley,  will 
enable  the  student  to  form  an  idea  of  the  general  process 
of  development.  A  linear  depression,  the  primitive  groove, 
makes  its  appearance  on  the  surface  of  the  blastoderm, 
arid  the  substance  of  the  mesoblast  along  each  side  of  this 
groove  grows  up,  carrying  with  it  the  superjacent  epiblast. 
Thus  are  produced  the  two  dorsal  lamince,  the  free  edges 
of  which  arch  over  toward  one  another,  and  eventually 
unite,  so  as  to  convert  the  primitive  groove  into  the  cere- 
bro-spinal  canal.  The  portion  of  the  epiblast  which  lines 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.  203 

this,  cut  off  from  the  rest,  becomes  thickened,  and  takes 
on  the  structure  of  the  brain,  or  encephalon,  in  the  region 
of  the  head ;  and  of  the  spinal  cord,  or  myelon,  in  the 
region  of  the  spine.  The  rest  of  the  epiblast  is  converted 
into  the  epidermis. 

The  part  of  the  blastoderm  which  lies  external  to  the 
dorsal  laminae  forms  the  ventral  lamince;  and  these  bend 
downward  and  inward,  at  a  short  distance  on  either  side 
of  the  dorsal  tube,  to  become  the  walls  of  a  ventral  or 
visceral  tube.  The  ventral  laminae  carry  the  epiblast  on 
their  outer  surfaces,  and  the  hypoblast  on  their  inner  sur- 
faces, and  thus,  in  most  cases,  tend  to  constrict  off  the 
central  from  the  peripheral  portions  of  the  blastoderm. 
The  latter,  extending  over  the  yelk,  incloses  it  in  a  kind 
of  bag.  This  bag  is  the  first  formed  and  the  most  con- 
stant of  the  temporary,  or  fostal  appendages  of  the  young 
vertebrate,  the  umbilical  vesicle. 

While  these  changes  are  occurring,  the  mesoblast  splits, 
throughout  the  regions  of  the  thorax  and  abdomen,  from 
its  ventral  margin,  nearly  up  to  the  notochord  (which  has 
been  developed,  in  the  meanwhile,  by  histological  differen- 
tiation of  the  axial  indifferent  tissue,  immediately  under 
the  floor  of  the  primitive  groove)  into  two  lamella.  One 
of  these,  the  visceral  lamella,  remains  closely  adherent  to 
the  hypoblast,  forming  with  it  the  splanchnopleure,  and 
eventually  becomes  the  proper  wall  of  the  enteric  canal ; 
while  the  other,  the  parietal  lamella,  follows  the  epiblast, 
forming  with  it  the  somatopleure,  which  is  converted  into 
the  parietes  of  the  thorax  and  abdomen.  The  point  of 
the  middle  line  of  the  abdomen  at  which  the  somato- 
pleures  eventually  unite,  is  the  umbilicus. 

The  walls  of  the  cavity  formed  by  the  splitting  of  the 
ventral  laminae  acquire  an  epithelial  lining,  and  become 
the  great  pleuroperitoneal  serous  membranes  (Huxley's 
Anatomy  of  Vertebraled  Animals). 

In  addition  to  the  umbilical  vesicle,  above  described  as 


204  THE    MICROSCOPIST. 

a  temporary  appendage,  the  foetus  has  other  special  struc- 
tures, derived  from  the  blastoderm.  Thus  the  somato- 
pleure  grows  up  over  the  embryo  arid  forms  a  sac  filled 
with  clear  fluid,  the  amnion.  The  outer  layer  of  the  sac 
coalesces  with  the  vitelline  membrane  to  form  the  chorion. 
The  attantois  begins  as  an  outgrowth  from  the  mesoblast. 
It  becomes  a  vesicle,  and  receives  the  ducts  of  the  primor- 
dial kidneys  or  Wolffian  bodies,  and  is  supplied  with  blood 
from  the  two  hypogastric  arteries  which  spring  from  the 
aorta.  The  allantois  is  afterwards  cast  off  by  the  contrac- 
tion of  its  pedicle,  but  a  part  of  its  root  is  usually  re- 
tained, and  becomes  the  permanent  urinary  bladder.  In 
the  Mammalia  the  allantois  conveys  the  embryonic  ves- 
sels to  the  internal  surface  of  the  chorion,  whence  they 
draw  supplies  from  the  vascular  lining  of  the  uterus. 

Foster  and  Balfour  recommend  that  the  study  of  em- 
bryonic development  should  commence  with  the  egg  of  a 
fowl  taken  at  different  times  from  a  brooding  hen,  or  an 
artificial  incubator.  The  egg  should  be  placed  on  a  hol- 
low mould  of  lead  in  a  basin,  and  covered  with  a  warm 
solution  of  salt  (7.5  per  cent.).  It  should  be  opened  with 
a  blow,  or  by  filing  the  shell.  With  the  naked  eye  or 
simple  lens,  lying  across  the  long  axis  of  the  egg,  may  be 
seen  the  pellucid  area,  in  which  the  embryo  appears  as  a 
white  streak.  The  mottled  vascular  area,  with  the  blood- 
vessels, and  the  opaque  area  spreading  over  the  yelk,  may 
be  observed.  The  blastoderm  may  be  cut  out  with  a  sharp 
pair  of  fine  scissors,  floated  into  a  watch-glass,  freed  from 
vitelline  membrane  and  yelk,  and  removed  (under  the  salt 
solution)  to  a  glass  slide.  A  thin  ring  of  putty  may  then 
be  placed  round  the  blastoderm,  which  is  covered  with 
salt  solution,  and  the  thin  glass  cover  put  on.  With  a 
low-power  objective  many  of  the  details  of  structure  may 
be  seen  in  an  embryo  of  thirty-six  to  forty-eight  hours 
incubation,  as  the  heart,  the  neural  tube,  the  first  cere- 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          205 

bral  vesicles,  the  folds  of  the  somatopleure  and  splanch- 
nopleure,  the  provertebne,  etc. 

To  prepare  sections  of  the  embryo,  it  must  be  first  hard- 
ened by  placing  the  slide  containing  it  in  a  solution  of  1 
per  cent,  chromic  acid  for  twenty-four  hours.  From  this 
it  should  be  removed  to  one  of  3  per  cent,  for  twenty -four 
hours  more  ;  then  for  a  similar  time  in  alcohol  of  70  per 
cent.,  then  in  alcohol  of  90  per  cent.,  and  lastly  in  abso- 
lute alcohol,  where  it  may  remain  till  required  for  section. 
Sometimes  picric  or  osmic  acid  is  used  for  hardening. 
The  embryo  may  be  stained  by  placing  it  in  Beale's  car- 
mine fluid  for  twenty-four  hours,  and  then  replacing  it  in 
absolute  alcohol  for  a  day  before  it  is  cut.  It  may  also 
be  stained  with  hsematoxylin  if  preferred.  The  specimen 
may  be  imbedded  in  paraffin,  wax,  and  oil,  or  a  mixture 
of  four  parts  of  spermaceti  to  one  part  of  cocoa  butter  or 
castor  oil.  If  there  are  cavities  in  the  object,  it  is  best 
to  saturate  it  first  with  oil  of  bergamot.  A  little  melted 
spermaceti  mixture  is  poured  on  the  bottom  of  a  small 
paper  box,  and  when  solid  the  embryo  is  placed  flat  on 
it,  the  superfluous  oil  removed  as  far  as  possible,  and  the 
warm  mixture  poured  on.  Bubbles  can  be  removed  with 
a  hot  needle.  A  mark  should  be  made  of  the  exact  posi- 
tion of  the  embryo.  Sections  may  be  cut  with  the  sec- 
tion-cutter or  a  sharp  razor,  and  if  the  spermaceti  mix- 
ture is  used,  the  razor  should  be  moistened  with  olive  oil. 
The  sections  should  be  floated  from  the  razor  to  the  slide, 
and  treated  with  a  mixture  of  four  parts  turpentine  and 
one  of  creasote.  They  may  then  be  mounted  in  balsam 
or  dammar  varnish. 

The  most  instructive  transverse  sections  of  an  early 
embryo  will  be  through  the  optic  vesicles,  the  hind  brain, 
the  middle  of  the  heart,  the  point  of  divergence  of  the 
splanchnopleure  folds,  the  dorsal  region,  and  a  point  where 
the  medullary  canal  is  still  open.  For  the  unincubated 
blastoderm  only  one  section,  through  the  centre,  is  re- 


206  THE    MICROSCOPIST. 

quired  to  show  the  formative  layers.  In  the  later  stages 
dissection  is  required,  and  is  best  performed  with  embryo 
preserved  in  spirit.  If  living  embryos  are  placed  in  spirit, 
a  natural  injection  of  the  vessels  may  be  obtained. 

III.  OKGAKS  OF  THE  BODY. 

Anatomists  usually  group  the  organs  into  systems,  as 
the  osseous,  muscular,  nervous,  vascular  systems,  etc.,  but 
for  histological  study  a  classification  based  on  physiologi- 
cal considerations  may  be  more  convenient  for  the  student. 

I.  VEGETATIVE  ORGANS. 

1.  Nutritive,  or  organs  pertaining  to  the  absorption  and 
distribution  of  pabulum,  including  the  digestive  and  cir- 
culatory organs. 

The  mucous  membrane  of  the  intestinal  canal  contains 
many  follicles  and  glands,  whose  secretions  serve  impor- 
tant offices  in  the  preparation  of  the  food.  These  will  be 
referred  to  in  the  next  section.  The  epithelium  of  the 
intestinal  canal  is  columnar,  except  in  the  oesophagus, 
where  it  is  laminated.  Beneath  the  glandular  layer  of 
the  stomach  is  a  stratum  of  fibrous  connective  tissue  and 
muscle  fibres  in  two  layers,  an  internal  with  transverse, 
and  an  external  with  longitudinal  fibres.  The  tissue  of 
the  small  intestine  beneath  the  epithelium  is  reticular 
connective,  entangling  lymphoid  cells.  The  structure  of 
the  large  intestine  is  similar  to  that  of  the  stomach.  The 
villi  of  the  small  intestine  begins  at  the  pylorus,  flat  and 
low  at  first,  but  becoming  conical,  and  finally  finger-like 
in  shape.  The  epithelium  of  the  villi  are  columnar,  with 
a  thickened  and  perforated  edge  (Plate  XXII,  Fig.  161). 
Between  the  epithelial  cells  of  the  villi,  peculiar  "goblet- 
cells"  are  often  found,  which  Frey  supposes  to  be  decay- 
ing cells.  The  reticular  connective  tissue  of  each  villus 
is  traversed  by  a  vascular  network,  a  lymphatic  canal  or 
lacteal,  and  delicate  longitudinal  muscular  fibres.  If  the 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.  ;       207 

villus  is  unusually  broad,  there  may  be  more  than  one 
lacteal.  The  lacteals  absorb  the  fluid  known  as  chyle. 
They  are  blind  ducts,  and  nitrate  of  silver  injections  show 
them  to  have  the  same  structure  as  other  lymphatics. 

The  lymphatic  radicles  are  widely  disseminated  through 
all  the  tissues  and  organs  of  the  body.  They  take  up  nu- 
tritive fluids,  either  from  the  alimentary  canal,  or  such  as 
have  transuded  from  the  capillaries  into  the  interstices  of 
the  body,  mingled  with  the  products  of  decomposition, 
and  convey  them  into  the  general  circulation.  Hyrtl's 
method  of  demonstrating  these  radicles  is  by  passing  a 
fine  canula  into  the  tissue  containing  lymphatics  and  forc- 
ing the  injection  by  gentle  pressure.  They  are  either  net- 
works, analogous  to  capillaries,  or  blind  passages  which 
unite  in  reticulations.  The  structure  of  the  vessels  has 
already  been  described,  page  201.  Lymphatics  and  capil- 
laries do  not  communicate  directly.  A  lymph-canal  may 
be  surrounded  by  capillaries,  or  run  alongside  of  a  capil- 
lary, or  a  lymphatic  sheath  may  envelop  a  bloodvessel. 
This  latter  plan  is  seen  in  the  nervous  centres,  and  has 
been  called  by  His  the  perivascular  canal  system. 

The  larger  lymphatic  trunks  are  interrupted  by  nodular 
and  very  vascular  organs,  the  lymphatic  glands.  These 
consist  of  the  reticular  connective  tissue  already  described, 
surrounded  by  an  envelope  of  ordinary  fibrous  tissue.  One 
or  more  afferent  lymphatic  vessels  penetrate  the  capsule, 
or  envelope,  and  similar  efferent  vessels  make  their  exit 
from  the  other  side.  Frey  describes  these  glands  as  con- 
sisting of  a  cortical  portion,  follicles,  and  a  medullary 
portion  composed  of  the  tubes  and  reticular  prolongations 
of  the  follicles  (Plate  XXII,  Fig.  1«2).  There  is  a  corn- 
plicate  system  of  communication  between  the  follicles. 
The  afferent  vessel  opens  into  the  investing  spaces  of  the 
follicle.  These  lead  into  the  lymph-passages  of  the  med- 
ullary portion,  from  the  confluence  of  which  the  radicles 
of  the  efferent  vessels  are  formed.  The  lingual  follicular 


208  THE    MICROSCOPIST. 

glands  and  tonsils,  the  solitary  and  agminated  glands  of 
the  intestine  (Peyer's  patches),  the  thymus,  and  the  spleen 
have  a  similar  structure,  and  are  called  lymphoid  organs. 

In  the  thoracic  duct  the  epithelium  is  inclosed  in  several 
layers  of  fibrous  membrane.  The  latter  contains  trans- 
verse muscular  fibres.  The  heart,  although  an  involuntary 
muscular  organ,  has  striated  muscular  fibres.  These  fibres 
are  not,  like  other  striped  muscles,  collected  into  bundles, 
but  are  reticular.  The  heart,  like  other  organs,  is  supplied 
with  lymphatics  and  bloodvessels.  The  cardiac  plexus  of 
nerves  consists  of  branches  from  the  vagus  and  sympa- 
thetic. Numerous  microscopic  nervous  ganglia  also  occur, 
especially  near  the  transverse  groove  and  septum  of  the 
ventricles.  It  is  thought  that  these  are  the  chief  centres 
of  energy,  so  that  the  heart  pulsates  after  its  removal  from 
the  body.  It  has  also  been  shown  recently  that  the  sym 
pathetic  and  vagus  filaments  are  in  antagonism,  so  that 
stimulation  of  the  vagus  interrupts  the  motor  influence  of 
the  sympathetic,  and  may  bring  the  heart  to  a  standstill 
in  a  condition  of  diastole. 

The  structure  of  bloodvessels  has  been  described  under 
the  head  of  vascular  tissue.  JSTo  special  boundary  exists 
between  capillaries  and  the  arteries  and  veins.  The  ar- 
rangement of  the  capillaries,  however,  is  various,  and 
often  so  characteristic  that  a  practiced  eye  can  generally 
recognize  an  organ  or  tissue  from  its  injected  capillaries. 
(Plate  XXII,  Figs.  163  to  1G8.)  For  methods  of  inject- 
ing, see  page  64.  Capillaries  form  either  longitudinal  or 
rounded  meshes.  The  muscular  network,  etc.,  is  extended, 
while  fat-cells,  the  alveoli  of  the  lungs,  lobules  of  liver, 
capillary  loops  of  papillae  in  skin  and  mucous  membranes, 
outlets  of  follicles,  etc.,  present  a  more  or  less  circular  in- 
terlacement. The  capillary  tube  lies  external  to  the  ele- 
mentary structure,  and  never  penetrates  its  interior. 

2.  Secretive  Organs. — True  secretions  serve  important 
offices  in  the  organism :  as  the  materials  of  reproduction ; 


PLATE  XXII. 


FIG.  161. 


FIG.  162. 


Intestinal  Villas. 


FIG. 163. 


Lymphatic  Gland. 
FIG. 164. 


Capillary  net-work  around  Fat-cells. 
FIG.  165. 


Capillary  net-work  of  Muscle. 
Via. 166. 


Distribution  of  Capillaries 
in  Mucous  Membrane. 

FIG. 167. 


Distribution  of  Capillary  bloodvessels 
in  Skin  of  Finger. 

FlG.  168. 


Villi  of  Small  Intestine  of  Monkey. 


Arrangement  of  the  Capillaries  of  the  air-cells  of 
the  Human  Lung. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          209 

milk  from  the  mammary  gland;  saliva,  gastric  juice  and 
pancreatic  fluid  for  digestion  ;  mucus,  sebaceous  matter, 
tears,  etc.  Excretions  result  from  waste  or  decomposi- 
tion, and  are  incapable  of  further  use;  as  carbonic  acid, 
separated  by  the  lungs ;  urea,  uric  acid,  etc.,  by  the  kid- 
neys ;  saline  matters,  from  kidneys  and  skin  ;  lactic  acid, 
portions  of  bile,  and  some  of  the  components  of  faeces. 

The  sweat  glands  in  the  skin  are  simply  convoluted  tubes 
lined  with  glandular  epithelium  and  surrounded  by  a 
basket-like  plexus  of  capillaries.  The  sebaceous  glands  are 
racemose,  and  often  open  into  the  hair-follicles. 

The  salivary  glands  are  complex  mucous  glands,  anc} 
the  saliva  secreted  by  them  is  a  complex  mixture.  The 
terminal  nerves  of  the  submaxillary  gland  have  been  traced 
to  the  nuclei  of  the  gland-cells. 

The  lingual  glands,  and  parotid,  partake  of  the  nature 
of  lymphoid  organs.  The  glands  of  the  oesophagus  are 
racemose.  In  the  stomach  there  are  two  kinds,  the  peptic, 
and  gastric  mucous  glands.  The  peptic  glands  are  blind 
tubes  closely  crowded  together  over  the  mucous  mem- 
brane, lined  with  columnar  epithelium  near  their  open- 
ings, and  gland-cells  below.  The  mucous  glands  are  nu- 
merous near  the  pylorus,  and  are  usually  branching  tubes. 
The  capillaries  are  arranged  in  long  rneshes  about  the 
peptic  glands,  and  form  a  delicate  network  in  the  submu- 
cous  tissue.  Numerous  lymphatic  radicles  communicate 
with  lymph-vessels  below  the  peptic  glands. 

The  small  intestine  contains  the  racemose  glands  of 
Brunner  and  the  tubular  follicles  of  Lieberkuhn,  together 
with  the  lymphoid  follicles  known  as  the  solitary  and 
agminated  glands  of  Peyer.  The  glands  of  Brunner  are 
confined  to  the  duodenum,  and  their  excretory  duct  and 
gland  vesicle  are  lined  by  columnar  epithelium.  Lieber- 
kuhn's  follicles  are  found  in  great  numbers  all  over  the 
small  intestine.  Peyer's  patches  are  most  numerous  in 
the  ileum.  They  are  accumulations  of  solitary  glands, 

14 


210  THE    MICROSCOPIST. 

and  their  structure  is  similar  to  the  follicles  of  a  lymphatic 
gland.  The  gland  vesicles  of  the  pancreas  are  roundish, 
and  like  other  salivary  glands  it  is  invested  with  a  vascu- 
lar network  with  rounded  meshes. 

The  liver  is  the  largest  gland  connected  with  nutrition. 
Few  animals  are  without  a  liver  or  its  structural  equiva- 
lent. In  polyps  the  liver  is  represented  by  colored  cells 
in  the  walls  of  the  stomach  cavity.  In  annelids  the  biliary 
cells  cluster  round  ceecal  prolongations  of  the  digestive 
cavity.  In  Crustacea  the  liver  consists  of  follicles,  and  in 
insects  of  tubes,  opening  into  the  intestine.  In  all  cases 
the  essential  elements  are  glandular  cells  containing  col- 
oring matter,  oil,  etc.  In  vertebrates  some  parts  of  the 
structure  have  not  been  decided  upon  without  controversy. 

In  man  the  liver  is  a  large,  solid,  reddish-brown  gland, 
about  twelve  inches  across,  and  six  or  seven  inches  from 
anterior  to  posterior  edge,  and  weighing  three  or  four 
pounds,  situated  in  the  right  hypochondrium,  and  reach- 
ing over  to  the  left.  It  is  divisible  into  right  and  left 
lobes  by  the  broad  peritoneal  ligament  above,  and  the 
longitudinal  fissure  beneath.  From  the  latter  a  groove 
passes  transversely  on  the  right  side,  lodging  the  biliary 
ducts,  sinus  of  the  portal  vein,  hepatic  artery,  lymphatics, 
and  nerves,  which  are  enveloped  in  areolar  tissue,  called 
the  capsule  of  Glisson.  From  this  groove  ramifications 
of  the  portal  canal  extend  through  the  liver,  so  numerous 
that  no  part  of  the  hepatic  substance  is  further  than  one- 
thirtieth  of  an  inch  from  them.  These  ramifications 
carry  the  branches  of  the  portal  vein  from  which  the 
capillary  plexus  surrounding  the  lobules  begin,  together 
with  the  bile-ducts,  hepatic  artery,  etc. 

The  hepatic  lobules  are  readily  distinguished  by  the 
naked  eye  in  many  mammals,  as  the  hog,  but  less  easily 
in  human  liver.  They  consist  essentially  of  innumerable 
gland-cells,  and  a  complex  network  of  vessels  which  tend 
towards  the  centre  of  the  lobule,  where  their  confluence 


PLATE  XXIII. 


Fio. 169. 


FIG.  170. 


Lobule  of  Liver. 


FIG. 171. 


Uriniferous  Tubes  of  Kidney. 


FIG.  173. 


Blood-vessels  of  Kidney. 


Tactile  Papillse. 


FIG.  174. 


FIG.  172. 


Alveoli  of  Lung. 


Taste-buds. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.         211 

forms  the  radicle  of  the  hepatic  vein  ;  while  externally 
the  lobules  are  bounded  by  branches  of  the  portal  vein 
and  biliary  canals  (Plate  XXIII,  Fig.  169).  The  hepatic 
artery  nourishes  the  proper  connective  tissue  of  the  organ,, 
and  its  venous  radicles  return  the  blood  to  the  portal 
vein.  The  liver  or  bile-cells  lie  between  the  meshes  of 
the  capillaries,  and  are  irregularly  polyhedral  from  pres- 
sure, soft,  granular,  and  nucleated.  Brown  pigment-graiv 
ules  and  fatty  globules  are  also  found  in  the  cells,  and  in* 
disease  in  increased  quantity.  These  bile-cells  are  inclosed 
in  a  delicate  reticulated  membrane,  and  Hering  considers- 
them  to  have  a  plexus  of  fine  bile-ducts  around  them. 

The  kidneys  are  two  large  bean-shaped  organs,  each 
covered  with  a  thin  but  strong  fibrous  envelope  or  tunic, 
which  is  continuous  round  the  organ  to  the  hilus,  where 
the  ureter  leaves  the  gland  and  the  bloodvessels  enter. 
Even  with  the  naked  eye  we  may  distinguish  in  a  section 
of  kidney  the  external  granular  cortex  and  the  fibrous  or 
striped  medullary  portion.  The  lines  of  the  latter  con- 
verge towards  the  hilus,  and  generally  in  a  single  conoid 
mass ;  but  in  man  and  some  other  animals  this  is  divided 
into  sections,  called  the  pyramids,  and  between  them  the 
cortical  substance  is  prolonged  in  the  form  of  septse,  while 
both  portions  contain  interstitial  connective  tissue.  Both 
the  cortical  and  medullary  portions  contain  long  branch- 
ing glandular  tubes,  called  the  uriniferous  tubes.  In  the 
medullary  part  these  tubes  are  straight  and  divide  at 
acute  angles,  while  in  the  cortex  they  are  greatly  convo- 
luted and  terminate  in  blind  dilatations,  the  capsules  of 
Bowman.  Staining  with  nitrate  of  silver  shows  the  cap- 
sules to  be  lined  with  delicate  pavement-epithelium.  The 
convoluted  tubes  proceeding  from  the  capsules,  containing 
thick  granular  gland-cells,  after  numerous  windings  in  the 
cortex,  arrive  at  the  medullary  portion,  where  each  pur- 
sues a  straight  course,  and  is  lined  with  flat  pavement- 
epithelium  similar  to  the  endothelium  of  vascular  tissue. 


212  THE    MICROSCOPIST. 


the  base  of  the  pyramids  these  tubes  curve  upwards, 
forming  the  looped  tubes  of  Henle.  The  recurrent  tubes 
enlarge,  and  exhibit  the  ordinary  cubical  gland-cell. 
These  tubes  also  become  more  tortuous,  and  empty  into 
others  of  larger  calibre,  called  collecting  tubes.  These 
are  lined  with  low  columnar  epithelium,  and  uniting  with 
similar  tubes  at  acute  angles,  give  exit  to  the  urine  at  the 
apex  of  the  papillae  in  the  pyramids  (Plate  XXIII,  Fig. 
170). 

The  bloodvessels  of  the  kidney  are  as  complex  as  the 
glandular  tissue.  Both  vein  and  artery  enter  at  the  hilus 
of  the  kidney,  and  after  giving  twigs  to  the  external 
tunic,  proceed  between  the  pyramids  as  far  as  their  bases. 
Here  they  give  off  curving  branches,  forming  imperfect 
arches  among  the  arteries,  and  complete  anastomosing 
rings  on  the  veins.  From  the  arterial  arcbes  spring  the 
branches  which  bear  the  glomeruli  of  the  cortical  sub- 
stance or  Malpighian  tufts  (Plate  XXIII,  a,  Fig.  171). 
The  afferent  vessel  of  the  glomerulus  subdivides,  and  after 
coiling  and  twisting  w7ithin  the  capsule  of  Bowman,  gives 
origin  to  the  efferent  vessel,  by  the  union  of  the  small 
branches  thus  formed.  This  efferent  vessel  breaks  up  into 
a  network  of  fine  capillaries,  with  elongated  meshes  sur- 
rounding the  straight  uriniferous  canals.  From  the  periph- 
ery of  this  network  somewhat  wider  tubes  are  given  off, 
which  surround  with  rounded  meshes  the  convoluted  tubes 
of  the  cortex. 

The  long  bundles  of  vessels  between  the  uriniferous  tubes 
of  the  medulla,  communicating  in  loops  or  forming  a  deli- 
cate network  round  the  mouths  of  the  canals  at  the  apex 
of  the  papillse  are  called  the  vasa  recta. 

The  ureters,  like  the  pelvis  of  the  kidney,  consist  of  an 
external  fibrous  tunic,  a  middle  layer  of  smooth  muscular 
fibres,  and  an  internal  mucous  membrane  with  a  layer  of 
epithelium.  The  bladder  is  covered  externally  with  a 
serous  membrane,  the  peritoneum.  The  female  urethra  is 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          213 

lined  by  mucous  membrane,  with  vascular  walls  full  of 
folds,  and  containing,  near  the  bladder,  a  number  of  mu- 
cous glands. 

3.  Respiratory   Organs. — The  lungs  receive  air  by  the 
trachea  and  venous  blood  from  the  right  side  of  the  heart 
to  transmit  to  the  left  side.     They  may  be  compared,  as 
to  form  and  development,  to  racemose  glands.     The  ex- 
cretory ducts  are  represented  by  the  bronchial  ramifica- 
tions, and  the  acini  by  the  air-vesicles. 

The  ciliated  mucous  membrane  of  the  bronchial  twigs 
gradually  loses  its  laminated  structure  until  only  a  single 
layer  remains.  Their  muscular  layer  also  ceases  before 
arriving  at  the  air-cells.  At  the  end  of  the  last  bronchial 
tubules  we  find  thin-walled  canals  called  alveolar  passages. 
These  are  again  subdivided  and  end  in  peculiar  dilatations 
called  primary  pulmonary  lobules,  or  infandibula  (Plate 
XXIII,  Fig.  172).  The  air-cells,  vesicles,  or  alveoli,  are 
sacciilar  dilatations  in  the  walls  of  the  primary  lobules, 
opening  directly  into  a  common  cavity.  Their  walls  con- 
sist of  delicate  membrane  of  connective  tissue,  often  con- 
taining black  pigment,  probably  from  inhalation  of  car- 
bonaceous matter,  or  a  deposit  of  melanin. 

The  pulmonary  artery  subdivides,  and  follows  the  rami- 
fications of  the  bronchi  to  the  pulmonary  vesicles.  Here 
a  multitude  of  capillary  tubes  form  a  network  over  the 
alveoli,  only  separated  from  the  air  by  the  most  delicate 
membrane  (Plate  XXII,  Fig.  168).  In  the  frog  we  find 
the  whole  respiratory  portion  lined  with  a  continuous 
layer  of  flattened  epithelia.  A  similar  lining  is  found  in 
the  mammalian  foetus,  but  in  the  adult  the  number  and 
character  of  the  epithelial  scales  is  greatly  changed.  Large 
non-nucleated  plates  are  seen  with  occasional  traces  of  the 
original  bioplasm.  In  inflammatory  affections,  however, 
these  may  multiply,  giving  rise  to  catarrhal  desquamation. 

4.  G-enerative  Organs. — The  histology  of  the  organs  of 
reproduction  is  quite  elaborate,  and  the  plan  of  this  work 


214  THE    MICROSCOPIST. 

only  permits  us  to  glance  at  the  essential  structures, 
which  are  the  seminiferous  tubules  for  the  secretion  of 
spermatozoa,  in  the  male,  and  the  ovary  for  the  production 
of  the  germ,  or  ovum,  in  the  female. 

The  tubuli  seminiferi  are  a  multitude  of  fine  and  tortuous 
tubules  contained  in  the  testis,  with  its  accessory  epididy- 
mis.  They  lie  in  the  interstices  of  sustentacular  connec- 
tive tissue,  and  consist  of  membranous  tubes  filled  with 
cells,  which  are  said  to  possess  amoeboid  motion.  During 
the  virile  period  these  glandular  tubes  generate  the  sper- 
matozoa, or  microscopic  seminal  filaments.  The  shape  of 
these  spermatozoa  is  filiform  in  all  animals,  but  vary  in 
different  species.  In  man  they  consist  of  an  anterior  oval 
portion,  or  head,  and  a  posterior  flexible  filament,  or  tail. 
Different  observers  have  taken  different  views  as  to  the 
origin  of  these  structures.  Some  suppose  them  the  product 
of  special  cells,  others  trace  them  to  the  nuclei  of  the 
glandular  epithelium,  while  others  regard  them  as  ciliated 
elements  formed  by  the  metamorphosis  of  entire  cells. 
Their  motions  baffle  all  attempts  at  explanation,  although 
quite  similar  to  those  of  ciliated  epithelium.  The  sperma- 
tozoa penetrate  by  their  movements  into  the  interior  of 
the  ovum,  in  order  to  impregnate  it,  and  in  the  mammalia 
in  considerable  numbers. 

The  ovary  may  be  divided  into  two  portions :  a  medul- 
lary substance,  which  is  a  non-glandular  and  very  vascular 
connective  tissue,  and  a  glandular  parenchyma  enveloping 
the  latter.  •  The  surface  of  the  ovary  uncovered  by  peri- 
toneum is  coated  with  a  layer  of  low  columnar  cells,  called 
the  germinal  epithelium.  Immediately  under  this  is  a 
stratum  called  the  zone  of  the  primordial  follicles,  or  cor- 
tical zone.  Here  the  young  ova  lie  crowded  in  layers. 
They  consist  of  granular  bioplasm,  containing  fatty  mol- 
ecules and  a  spherical  nucleus.  They  are  probably  de- 
veloped by  a  folding  in  of  the  germinal  epithelium.  To- 
ward the  internal  portion  of  the  ovary  the  follicles  become 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          215 

more  highly  developed,  and  the  ovum  contained  in  them  is 
also  increased  in  size  and  enveloped  in  a  distinct  mem- 
brane. There  are  from  twelve  to  twenty  mature  follicles 
in  the  ovarium,  named,  from  their  discoverer,  Graafian 
follicles.  Each  has  an  epithelial  lining,  in  which  the  ovum 
is  imbedded.  The  capsule  of  the  ovum  is  known  as  the 
zona  pellucida,  or  chorion,  and  the  albuminous  cell-body  is 
the  vitellus.  The  nucleus  is  situated  excentrically,  and  is 
called  the  vesicula  germinativa,  or  germinal  vesicle  of  Pur- 
kinje.  "Within  it  is  a  round  and  highly  refractive  nucle- 
olus,  the  macula  germinativa,  or  germinal  spot  of  Wagner. 
A  Graafian  vesicle  bursts  and  an  ovum  is  liberated  at 
every  menstrual  period.  During  the  progress  of  the  latter 
down  the  Fallopian  tube  to  the  uterus,  impregnation  may 
take  place  by  the  penetration  of  spermatozoa  into  its  yelk. 
Then  the  inherent  vital  energies  of  the  cell  are  aroused, 
and  the  process  of  segmentation  begins.  Unimpregnated 
ova  are  destroyed  by  solution.  The  ruptured  and  emptied 
Graafian  vesicle  becomes  filled  up  with  cicatricial  connec- 
tive tissue,  which  constitutes  what  is  called  the  corpus 
luteum,  after  which  it  gradually  disappears. 

II.  ORGANS  OF  ANIMAL  LIFE. 

1.  Locomotive. — The  microscopic  structure  of  bone  and 
muscle  has  been  described  in  connection  with  elementary 
tissues.     Tendons  and  fascias  belong  to  the  connective 
tissues. 

2.  Sensory. — The  nervous  apparatus  of  the  body,  whose 
histological  elements  were  treated  of  on  a  previous  page, 
has  been  classified  physiologically  into: 

1.  The  sympathetic  system,  consisting  of  a  chain  of  gan- 
glia on  each  side  of  the  vertebral  column,  with  commu- 
nicating cords  or  extensions  of  ganglia,  visceral  nerves, 
arterial  nerves,  and  nerves  of  communication  with  the 
cerebral  and  spinal  nerves.  The  chief  structural  differ- 


21(3  THE    MICROSCOPIST. 

ence  between  tins  and  the  cerebro-spinal  system  is  that  in 
the  latter  the  nerve-cells  form  large  masses,  and  the  union 
of  its  parts  is  effected  by  means  of  central  fibres,  while  in 
the  sympathetic  the  cells  are  more  widely  separated,  and 
union  between  them  and  with  the  cerebro-spinal  axis  is 
by  means  of  peripheral  fibres.  The  sympathetic  is  con- 
sidered a  motor  and  sensitive  nerve  to  internal  viscera, 
and  to  govern  the  actions  of  bloodvessels  and  glands. 

2.   The  cerebro-spinal  system,  divided  into : 

(1.)  A  system  of  ganglia  subservient  to  reflex  actions, 
the  most  important  of  which  is  the  spinal  cord,  where  the 
gray  or  vesicular  nervous  matter  forms  a  continuous  tract 
internally. 

(2.)  A  ganglionic  centre  for  respiration,  mastication, 
deglutition,  etc.,  writh  a  series  of  ganglia  in  connection 
with  the  organs  of  special  sense:  the  medulla  oblongata, 
with  its  neighboring  structures;  the  mesocephalon,  cor- 
pora striata,  and  optic  thalami. 

(3.)  The  cerebellum,  a  sort  of  offshoot  from  the  upper 
extremity  of  the  medulla,  for  adjusting  and  combining 
voluntary  motions. 

(4.)  The  cerebrum,  cerebral  hemispheres,  or  ganglia, 
which  are  regarded  as  the  principal  organs  of  voluntary 
movements.  In  the  lower  vertebrates  the  hemispheres 
are  comparatively  small,  so  as  not  to  overlap  the  other 
divisions  of  the  brain ;  but  in  the  higher  Mammalia  they 
extend  over  the  olfactory  lobes  and  backward  over  the 
optic  lobes  and  cerebellum,  so  as  to  cover  these  parts, 
while  they  also  extend  downward  toward  the  base  of  the 
brain.  In  the  lower  vertebrates,'  also,  the  surface  of  the 
hemispheres  is  smooth,  while  in  the  higher  it  is  compli- 
cated by  ridges  and  furrows. 

(5.)  The  cerebral  and  spinal  nerves.  The  spinal  nerves 
arise  in  pairs,  generally  corresponding  with  the  vertebrae. 
Each  has  two  roots,  one  from  the  dorsal,  and  one  from 
the  ventral  region  of  its  half  of  the  cord.  The  former 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          217 

root  has  a  ganglionic  enlargement,  and  contains  only  sen- 
sory fibres ;  the  latter  has  no  ganglion,  and  contains  only 
motor  fibres. 

The  cerebral  nerves  are  those  given  off  from  the  base 
of  the  brain.  Some  of  these  minister  to  special  sensation, 
as  the  olfactory,  optic,  auditory,  part  of  the  glosso-pha- 
ryngeal,  and  the  lingual  branch  of  the  trifacial  nerves. 
Some  are  nerves  of  motion,  as  the  motor  oculi,  patheti- 
cus,  part  of  the  third  branch  of  the  fifth  pair,  the  abdu- 
cens,  the  facial  and  the  hypoglossal  nerves.  Others  are 
nerves  of  common  sensation,  as  the  fifth,  and  part  of  the 
glosso-pharyrigeal  nerves.  Others,  again,  are  mixed,  as 
the  pneurnogastric  and  spinal  accessory  nerves. 

The  minute  structure  of  the  central  organs  of  the  ner- 
vous system  is  excessively  complicate  and  full  of  details. 
Hardening  with  chromic  acid  and  bichromate  of  potash 
is  generally  advisable  before  examination.  This  should 
be  done  with  small  pieces  in  a  large  quantity  of  the  fluid. 
One-eighth  to  one-half  grain  of  bichromate,  or  0.033  to 
0.1  grain  of  chromic  acid,  to  the  ounce  of  water  should 
be  used,  the  strength  gradually  increased  from  day  to 
day.  After  such  maceration  for  several  days,  a  drop  of  a 
28  per  cent,  solution  of  caustic  potash  may  be  added  to 
one  ounce  of  water,  and  the  specimen  soaked  in  it  for  an 
hour,  to  macerate  the  connective  tissue.  After  again  soak- 
ing in  graduated  solutions  of  the  bichromate,  up  to  two 
grains  to  the  ounce,  the  tissue  may  be  carefully  picked 
apart  under  the  dissecting  microscope.  In  such  manner 
Deiters  discovered  the  two  kinds  of  processes  in  the  multi- 
polar  ganglion-cells.  Gerlach  placed  thin  sections  for  two 
or  three  days  in  0.01  to  0.02  per  cent,  solutions  of  bichro- 
mate of  ammonia,  and  picked  them  apart  after  staining 
with  carmine. 

Lockhart  Clarke  placed  parts  of  the  spinal  cord  in  equal 
parts  of  alcohol  and  water  for  a  day,  then  for  several  days 
in  pure  alcohol,  till  thin  sections  could  be  made.  These 


218  THE    MICROSCOPIST. 

were  immersed  for  an  hour  or  two  in  a  mixture  of  one  part 
acetic  acid  and  three  parts  alcohol,  to  render  the  gray 
matter  transparent  and  the  fibrous  elements  prominent. 

Sections  may  he  stained  with  carmine  and  mounted  in 
glycerin  or  balsam  (see  Chapter  Y). 

(6.)  Organs  of  special  sense : 

a.  Organs  of  Touch. — The  tactile  papillae  of  the  skin 
and  Pacinian  corpuscles  may  be  studied  in  thin  sections 
of  fresh  or  dried  skin.     Treatment  with  dilute   acetic 
acid,  or  acetic  acid  and  alcohol,  and  staini-ng  with  car- 
mine, or  chloride  of  gold,  is  recommended.     The  papillae 
are  made  up  of  connective  tissue,  into  which  nervous  fila- 
ments enter,  and  end  in  peculiar  tactile  corpuscles  (Plate 
XXIII,  Fig.  173).     The  structure  of  the  skin  itself,  with 
its  various  layers  and  sudoriparous  glands,  may  be  seen 
in  such  sections. 

b.  Organs  of  Taste.— The  terminations  of  the  gustatory 
nerves  of  the  tongue  are  yet  imperfectly  known.     In  the 
circumvallate  papillae,  on  the  side  walls,  certain  structures 
are  found,  called  gustatory  buds  or  taste-cups  (Plate  XXIII, 
Fig.  174).     They  consist  of  flattened  lanceolate-cells,  ar- 
ranged like  the  leaves  of  a  flower-bud,  and  containing 
within  them  fusiform  gustatory  cells,  which  end  in  rods, 
and  filaments  projecting  from  the  rods  above  the  buds 
are  seen  in  some  animals.     Underneath  is  a  plexus  of  pale 
and  medullated  nerve-fibres.     The  mode  .of  nervous  ter- 
mination in  the  fungiform  papillae  is  not  known.     For  pri- 
mary examination,  sections  of  the  dried  tongue  may  be 
softened  in  dilute  acetic  acid  and  glycerin,  or  hardened  in 
osmic  acid.     For  the  finer  structure,  maceration  in  iodine 
serum,  and  immersion  in  one-half  per  cent,  chromic  acid, 
with   an   equal   quantity   of  glycerin,  is   recommended. 
Careful  picking  under  the  simple  microscope  is  necessary. 
Sections  may  also  be  stained  with  chloride  of  gold. 

c.  Organs  of  Smell. — In  the  olfactory  regions,  which  are 
patches  of  yellowish  or  brownish  color  on  the  upper  and 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.         219 

deeper  part  of  the  nasal  cavity,  we  find  nucleated  cylin- 
drical cells  taking  the  place  of  ordinary  ciliated  epithe- 
lium, and  sending  processes  downward,  which  communi- 
cate with  each  other,  forming  a  delicate  network  (Plate 
XXIV,  Fig.  175).  Between  these  cells  we  find  the  olfac- 
tory cells,  spindle-shaped  nucleated  bodies,  extending  up- 
ward into  a  fine  rod  and  downward  into  a  varicose  fila- 
ment. In  hirds  and  amphibia  these  rods  are  terminated 
by  delicate  hairs,  some  of  which  have  ciliary  motion. 
Beneath  these  structures  are  peculiar  glands,  consisting 
of  pigmented  gland-cells.  They  are  called  Bowman's 
glands.  The  branches  of  the  olfactory  nerve  proceed  be- 
tween these  glands  and  branch  out  into  fine  varicose  fila- 
ments, which  are  supposed  to  communicate  with  the 
olfactory  cells.  Hardening  in  chromic  acid,  or  Muller's 
fluid,  or  a  concentrated  solution  of  oxalic  acid,  or  one- 
half  to  one  per  cent,  solution  of  sulphuric  acid,  is  neces- 
sary for  the  preservation  of  these  delicate  structures. 

d.  Organs  of  Sight. — As  in  the  sense  of  touch  certain 
tactile  papillae  detect  deviations  from  the  general  surface  ; 
and  in  that  of  taste  special  rod-like  end  organs  and  their 
covering  bulbs  distinguish  the  solutions  of  different  sapid 
substances ;  and  as  in  smelling,  not  the  whole  organ  but 
olfactory  regions,  with  peculiar  cells  and  nervous  rods, 
discriminate  mechanical  or  chemical  odors,  so  in  vision  a 
special  apparatus  is  provided  to  perceive  the  wonderful 
variety  of  colors  and  forms.  The  minute  structure  of 
organs  becomes  more  complex  in  proportion  as  they  serve 
the  higher  functions  of  mind. 

The  various  tunics  and  accessory  structures  of  the  eye 
are  described  in  most  text-books  ;  we  here  limit  ourselves 
to  a  brief  reference  to  those  refracting  and  receptive  struc- 
tures whose  office  it  is  to  translate  the  phenomena  of  light 
into  those  of  nervous  conduction. 

Externally,  we  have  in  front  of  the  eye  the  transparent 
cornea.  This  is  made  of  connective  tissue  with  cells,  bun- 


220  THE    MICROSCOPIST. 

dies  of  fibres,  and  cavities  containing  cells.  Its  tissues  are 
in  layers,  as  follows :  1.  External  epithelium,  flat  and 
laminated.  2.  Anterior  basement-membrane  or  lamina. 
3.  True  corneal  tissue.  4.  Membrane  of  Descemet  or 
Demours.  5.  Endotbelium  witb  flat  cells  (Plate  XXIY, 
Fig.  176).  The  cells  of  corneal  tissue  are  of  two  forms. 
The  first  are  wandering  or  amoeboid  cells,  and  may  be 
seen  in  a  freshly  extirpated  frog's  cornea  placed  underside 
up,  with  aqueous  humor  in  a  moist  chamber,  on  the  stage 
of  the  microscope.  If  a  small  incision  be  made  at  the 
margin  of  the  cornea  of  a  living  frog  a  few  hours  before 
its  extraction,  and  vermilion,  carmine,  or  anilin  blue  is 
rubbed  in,  the  cells  which  have  absorbed  the  coloring 
matter  will  be  found  at  some  distance  afterwards,  having 
wandered  like  leucocytes  or  pus-cells  elsewhere.  Their 
origin  may  be  from  blood  or  true  corneal  corpuscles,  or 
both.  The  second  form,  or  corneal  corpuscles,  are  im- 
movable, flat,  with  branching  or  stellate  processes.  They 
may  be  demonstrated  by  staining  with  chloride  of  gold 
or  nitrate  of  silver.  The  bundles  of  fibrillar  substance  in 
the  cornea  pass  in  various  directions,  and  the  natural 
cavities  in  it  contain  the  corneal  cells.  As  stated,  the 
nerves  of  the  cornea  have  been  traced  to  the  external 
epithelium,  which  sometimes  contains  serrated  (riff  or 
stachell)  cells. 

The  aqueous  humor  is  structureless,  but  the  vitreous 
humor  is  supposed  to  have  delicate  membranous  septa. 
The  crystalline  lens  consists  of  a  capsule  inclosing  a  tissue 
of  fine  transparent  fibres  or  tubules,  which  are  of  epithe- 
lial origin.  These  fibres  are  flat,  and  often  have  serrated 
borders,  especially  in  fishes. 

The  retina,  or  nervous  portion  of  the  eye,  is  the  most 
important,  as  its  delicacy  and  liability  to  decomposition 
render  it  the  most  difficult  object  of  microscopic  exami- 
nation. 

"We  must  dismiss  the  popular  notion  of  minute  images 


THE  MICROSCOPE  IN  ANIMAL  HISTOLOGY.    221 

produced  on  the  retina  by  the  lens  to  be  viewed  by  the 
mind.  The  lens  does,  indeed,  form  an  image  on  the  mem- 
brane, so  it  would  on  glass  or  paper,  but  the  real  action 
of  the  vibrations  of  light  upon  the  nervous  conductors  is 
not  thus  to  be  explained. 

The  complex  structure  of  the  retina  is  only  recently 
known,  and  it  may  be  that  many  laws  of  light  yet  un- 
known are  to  be  exhibited  by  its  means,  as  well  as  much 
that  relates  to  the  connection  of  the  perceiving  thinking 
mind  and  the  external  world. 

Muller's  fluid,  concentrated  solution  of  oxalic  acid,  0.6 
per  cent,  solution  of  sulphuric  acid,  and  0.1  to  2  per  cent, 
solutions  of  osmic  acid,  may  be  used  for  hardening,  but 
very  delicate  dissection  is  required  for  demonstration. 
Rutherford  recommends  chromic  acid  and  spirit  solution, 
1  gramme  of  chromic  acid  in  20  c.c.  of  water,  and  180  c.c. 
of  methylated  spirit  added  slowly. 

The  retina  consists  of  the  following  layers  :  1.  The 
columnar  layer,  or  layer  of  rods  and  cones.  2.  Membrana 
limitans  externa.  3.  External  granular  layer.  4.  Inter- 
granular  layer.  5.  Internal  granular  layer.  6.  Molecular 
layer.  7.  Ganglionic  cell  layer.  8.  Expansion  of  optic 
nerve.  9.  Membrana  limitans  interna.  To  these  may  be 
added :  10.  The  pigment  layer,  often  described  as  the 
pigmented  epithelium  of  the  choroid,  into  which  the  rods 
and  cones  project.  These  layers  are  composed  of  two 
different  elements,  mutually  blended,  a  connective-tissue 
framework  of  varying  structure  in  the  different  layers, 
and  a  complex  nervous  tissue  of  fibres,  ganglia,  rods,  and 
cones.  Plate  XXIV,  Fig.  177,  is  a  diagram  of  these 
separate  structures,  after  M.  Shultze,  in  Strieker's  Man- 
ual of  Histology. 

The  structure  of  the  rods  and  cones  is  complex,  and 
varies  in  different  animals.  The  rods  readily  decompose, 
becoming  bent  and  separated  into  disks,  but  examination 
of  well-preserved  specimens  shows  them  to  have  a  fibril- 


222  THE    MICROSCOPIST. 

lated  outer  covering.  In  addition,  certain  globular  or 
lenticular  refractive  bodies,  of  different  shape  and  color 
in  different  animals,  are  found  in  these  structures  (Plate 
XXI Y,  Fig.  178),  which  doubtless  are  designed  to  give 
the  rays  of  light  such  a  direction  for  final  elaboration  in 
the  outer  segment  as  they  could  not  receive  from  the 
coarser  refractive  apparatus  in  the  front  of  the  eye. 

e.  Organs  of  Hearing. — These  are  most  intimately  con- 
nected with  mental  functions,  because  of  language,  which 
is  the  highest  sensual  expression  of  mind.  Hence  the 
structure  of  these  organs  is  most  delicate  and  complex. 

The  labyrinth  is  the  essential  part  of  the  organ,  con- 
sisting in  man  of  the  vestibule,  the  semicircular  canals, 
and  the  cochlea.  Sonorous  undulations  are  propagated 
to  the  fluid  in  the  labyrinth  through  the  tympanum  and 
chain  of  otic  bones. 

The  auditory  nerves  are  distributed  to  the  ampullae  and 
sacculi  of  the  vestibule,  and  to  the  spiral  plate  of  the 
cochlea.  At  the  terminal  filaments  in  the  sac  of  the 
vestibule,  crystals,  called  otoliths,  of  shapes  differing  in 
various  animals,  are  inclosed  in  membrane.  Hasse  con- 
siders them  to  be  vibrating  organs,  but  Waldeyer  regards 
their  function  to  be  that  of  dampening  sound. 

As  we  distinguish  in  sounds  the  various  qualities  of 
pitch,  intensity,  quality,  and  direction,  it  is  probable  that 
there  is  a  special  apparatus  for  each,  but  histology  has 
not  yet  established  this  fully.  Kolliker  thinks  the  gan- 
glionic  termination  of  the  cochlear  nerve  renders  it  proba- 
ble that  it  only  receives  sonorous  undulations.  The  ex- 
periments of  Flourens  seem  to  show  that  the  semicircular 
canals  influence  the  impression  of  direction  of  sound. 

In  the  sacs  of  the  vestibule  and  ampullae,  the  nerve- 
fibres  are  confined  to  a  projection  of  the  walls  called  the 
septum  nerveum.  Here  are  found  cylinder-  and  fibre-cells, 
with  rods,  basal-cells,  and  nerves.  But  it  is  in  the  lamina 
spiralis.of  the  cochlea  that  the.  most  elaborate  organ, 


PLATE  XXIV. 


FIG. 175. 


FIG. 176. 


Olfactory  cells. 


Section  of  Cornea. 


FIG. 177. 


FIG.  179. 


Connective-tissue  and  nerve-elements  of  Retina. 
Showing  rods  and  cones. 


Section  of  Cochlea:— v,  seal  a  vestibuli;  T,  scala 
tympani;  c,  canal  of  Cochlea;  R,  Reissner's  mem- 
brane, attached  at  a  to  the  habenula  sulcata;  6, 
connective-tissue  layer ;  c,  organ  of  Corti. 


FIG.  178. 


FIG.  180. 


Refractive  bodies  in  the  rods  and  cones. 


FIG.  181. 


Corti's  organ,  from  above. 


Section  of  Corti's  organ. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          223 

called  from  its  discoverer  the  organ  of  Corti,  is  found. 
Kolliker  considers  the  free  position  of  the  expanded  por- 
tion of  the  nerve,  and  the  extent  of  surface  over  which 
its  terminal  fibres  are  spread,  to  constitute  it  an  organ  of 
great  delicacy,  enabling  us  to  distinguish  several  sounds 
at  once  and  to  determine  their  pitch.  There  is  a  striking 
analogy  between  the  visual  and  auditory  apparatus  in  the 
ganglionic  structure  of  the  nerve-structure.  Plate  XXIV, 
Fig.  179,  represents  a  vertical  section  through  the  tube 
of  the  cochlea;  and  Plate  XXIY,  Figs.  180  and  181,  the 
vestibular  aspect  and  a  vertical  section  of  Corti's  organ. 

Waldeyer  recommends  examination  of  the  cochlea  in  a 
fresh  state  and  in  aqueous  humor.  Preparations  in  osmic 
acid  and  chloride  of  gold  are  also  useful.  For  sections  he 
removes  much  of  the  bony  substance  of  large  cochleae  with 
cutting  pliers,  opens  the  membrane  in  several  places,  and 
places  the  specimen  in  0.001  per  cent,  of  chloride  of  palla- 
dium, or  0.2  to  1  per  cent,  osmic  acid  solution  for  twenty- 
four  hours,  then  for  the  same  time  in  absolute  alcohol. 
It  is  then  treated  with  a  fluid  composed  of  0.001  per  cent, 
chloride  of  palladium  with  one-tenth  part  of  J  to  1  per 
cent,  muriatic  or  chromic  acid,  to  deprive  it  of  earthy 
salts.  It  is  then  washed  in  absolute  alcohol,  and  inclosed 
in  a  piece'  of  marrow  or  liver,  and  placed  to  harden  in 
alcohol  again.  The  hollows  of  the  cochlea  may  be  filled 
with  equal  parts  of  gelatin  and  glycerin  before  they  are 
inclosed.  Sections  must  be  cut  with  a  sharp  knife. 

Rutherford  advises  the  softening  of  the  bone  and  hard- 
ening of  other  tissues  by  maceration  in  chromic  acid  and 
spirit  (1  gramme  of  chromic  acid  in  20  c.c.  of  water,  and 
180  c.c.  of  methylated  spirit  slowly  added).  For  sections 
he  commends  Strieker's  mode  of  imbedding  in  gum.  Place 
the  cochlea  in  a  small  cone  of  bibulous  paper,  containing 
a  strong  solution  of  gum  arabic,  for  four  or  five  hours ; 
then  immerse  the  cone  in  methylated  spirit  for  forty-eight 


224  THE    MICROSCOPIST. 

hours,  or  until  the  gum  is  hard  enough.     The  sections 
may  be  stained  with  carmine,  logwood,  silver,  or  gold. 

The  following  suggestions  from  Rutherford's  Outlines 
of  Practical  Histology,  will  be  of  service  to  the  student  in 
this  department : 

Most  of  the  tissues  required  may  be  obtained  from  the 
cat  or  guinea-pig.  Feed  the  cat,  and  an  hour  or  so  after 
place  it  in  a  bag;  drop  chloroform  over  its  nose  until  it  is 
insensible.  Open  the  chest  by  a  linear  incision  through 
the  sternum,  and  allow  the  animal  to  bleed  to  death  from 
a  cut  in  the  right  ventricle. 

Divide  the  trachea  below  the  cricoid  cartilage  and  in- 
ject it  with  |  per  cent,  chromic  acid  fluid  ;  tie  it  to  prevent 
the  escape  of  fluid,  and  place  the  distended  lungs  in  the 
same  fluid,  and  cover  them  with  cotton-wool.  Change 
the  fluid  at  the  end  of  eighteen  hours.  Allow  them  to 
remain  in  this  fluid  for  a  month,  then  transfer  to  methy- 
lated spirit  till  needed  for  mounting. 

Open  by  a  linear  incision  the  oesophagus,  stomach,  large 
and  small  intestines,  and  wash  them  with  salt  solution  (£• 
per  cent.).  Place  a  portion  of  small  intestine  in  chromic 
and  bichromate  fluid  (1  gramme  chromic  acid  and  2 
grammes  potassium  bichromate  in  1200  c.c.  water)  for  two 
weeks  (change  the  fluid  at  the  end  of  eighteen  hours),  and 
then  in  methylated  spirit  till  required.  Act  similarly 
with  parts  of  oesophagus,  stomach  and  large  intestine,  in 
J  per  cent,  chromic  acid  for  three  or  four  weeks.  A  por- 
tion of  stomach  may  be  placed  in  Muller's  fluid  till  re- 
quired for  preparation  of  non-striped  muscle,  and  of  the 
gastric  follicles. 

The  bladder  may  be  treated  as  the  small  intestine. 
•  Divide  one  kidney  longitudinally,  and  the  other  trans- 
versely, and  place  in  Muller's  fluid.  Change  the  fluid  in 
eighteen  hours,  and  after  four  weeks  transfer  to  methy- 
lated spirits.  They  will  be  ready  for  use  in  two  weeks 
after. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          225 

'Cut  one-half  of  the  liver  into  small  pieces  and  prepare 
as  the  kidneys.  The  tongue,  divided  transversely  into  five 
or  six  pieces,  the  spleen,  uterus,  and  thin  muscles  from 
limbs  or  abdomen,  in  J  per  cent,  chromic  acid.  Change  as 
before,  and  in  a  month  to  methylated  spirit. 

Testis  of  dog,  freely  incised,  and  ovaries  of  cat  or  dog, 
in  Muller's  fluid,  and  after  three  weeks  to  methylated 
spirits. 

Divide  the  eyes  transversely  behind  the  lens.  Remove 
the  vitreous.  Place  posterior  halves  in  chromic  and  spirit 
solution.  Change  in  eighteen  hours.  Transfer  to  methy- 
lated spirit  in  ten  days.  Place  the  lens  in  Muller's  fluid 
for  five  weeks,  and  then  in  methylated  spirits.  The  cor- 
nea may  remain  in  J  per  cent,  chromic  acid  for  a  month, 
and  then  in  methylated  spirit. 

Cautiously  open  the  cranial  and  spinal  cavities.  Re- 
move brain  and  cord,  and  strip  oft'  arachnoid.  Partially 
divide  the  cord  into  pieces  a  half  inch  long.  Partially 
divide  the  brain  transversely  into  a  number  of  pieces. 
Place  in  a  cool  place  in  methylated  spirits  for  eighteen 
hours.  Transfer  cord  to  \  per  cent,  chromic  acid  for  six 
or  seven  weeks.  Change  in  eighteen  hours.  Prepare  the 
sciatic  nerve  in  the  same  manner.  Place  the  brain  in 
chromic  and  bichromate  fluid.  Change  in  eighteen  hours, 
and  then  once  a  week,  until  the  brain  is  hard.  If  not 
leathery  in  six  weeks  place  in  J  per  cent,  chromic  acid  for 
two  weeks,  and  then  in  methylated  spirits.  Support  the 
brain  and  cord  on  cotton-wool  in  the  hardening  fluid. 

Remove  muscles,  but  not  periosteum  from  bones  of 
limbs,  and  both  from  the  lower  jaw.  Divide  the  bones 
transversely  in  two  or  three  places,  and  put  them  in  chro- 
mic and  nitric  fluid  (chromic  acid,  1  gram  ;  water,  200 
cc.  ;  then  add  2  cc.  nitric  acid).  Change  the  fluid  often 
until  the  bone  is  soft  enough,  and  transfer  to  methylated 
spirits.  If  not  complete  in  a  month,  double  the  quantity 
of  nitric  acid  in  the  fluid. 

15 


226  THE    MICROSCOPIST. 

Place  a  piece  of  human  scalp,  skin  from  palmar  surface 
of  finger,  and  skin  of  dog  (for  muscles  of  hair-follicles)  in 
chromic  and  spirit  fluid.  In  a  month  transfer  to  methy- 
lated spirit. 

Remove  the  petrous  portion  of  temporal  bone,  open  the 
tympanum,  pull  the  stapes  from  the  oval  fenestra,  and 
place  the  cochlea  in  chromic  and  spirit  fluid.  Change  in 
eighteen  hours,  and  at  the  end  of  seven  days,  if  a  brown 
precipitate  falls,  change  fluid  every  third  day.  On  the 
tenth  or  twelfth  day  transfer  to  chromic  and  nitric  fluid. 
Change  frequently  till  the  bone  is  soft.  Then  place  it  in 
methylated  spirit.  The  cochlea  of  the  guinea  pig  pro- 
jects into  the  tympanum,  and  is,  therefore,  convenient  for 
enabling  the  student  to  see  how  the  cone  is  to  be  sliced 
when  sections  are  made. 

Too  long  exposure  to  chromic  acid  renders  tissues  fria- 
ble, and  prevents  staining  with  carmine. 

Methylated  spirit  is  ordinary  alcohol  containing  10  per 
cent,  of  wood-naphtha,  and  is  used  in  England  as  a  sub- 
stitute for  alcohol,  since  it  is  free  of  duty  for  manufactur- 
ing purposes. 


CHAPTER  XIII. 

THE    MICROSCOPE   IN   PATHOLOGY. 

PATHOLOGICAL  histology  treats  of  the  minute  anatomy 
of  the  tissues  and  organs  in  disease,  and  is  essential  to  a 
knowledge  of  structural  changes  in  the  body.  Since  the 
old  method  of  judging  solely  by  symptoms  has  given  place 
to  the  more  rational  observation  of  the  actual  changes 
produced,  the  microscope  has  become  an  indispensable  aid 
to  practical  medicine.  As  anatomy  would  be  coarse  and 
imperfect  without  histology,  so  pathological  histology 


THE    MICROSCOPE    IN    PATHOLOGY.  227 

perfects  pathology,  and  guides  to  right  conclusions  the 
seeker  after  positive  truth  in  medicine. 

Our  plan  forbids  an  extensive  outline  of  the  facts  of 
morbid  anatomy.  We  propose  merely  such  a  classifica- 
tion of  the  microscopic  appearances  of  diseased  structures 
as  may  serve  to  guide  the  student  and  busy  practitioner 
in  actual  observation. 

PREPARATION   OF    SPECIMENS. 

Much  may  be  learned  by  the  examination  of  a  patho- 
logical specimen  without  any  preparation  whatever,  or 
with  the  use  of  indifferent  fluids  (see  Chapter  V).  A  thin 
section  may  be  made  under  water  with  a  Valentin's  knife, 
or  a  small  portion  may  be  snipped  off  with  curved  scis- 
sors and  teased  with  fine  needles.  The  freshly-cut  sur- 
face of  tumors  may  be  gently  scraped  with  a  knife  and 
the  separated  elements  examined  in  glycerin  and  water. 

For  a  thorough  examination  it  will  be  necessary  to 
harden,  stain,  and  make  thin  sections,  as  described  in 
Chapter  V  and  at  page  224.  Mtiller's  fluid,  page  68,  will 
be  found  most  generally  useful  for  morbid  specimens. 
After  small  pieces  have  lain  some  time  in  this  they  can  be 
still  further  hardened  by  absolute  alcohol.  Before  cut- 
ting thin  sections,  either  by  hand  or  with  a  section-cutter, 
the  specimen  will  require  to  be  imbedded  so  as  to  be 
readily  held  and  cut  without  tearing.  A  mixture  of  wax 
or  paraffin  and  olive  oil  is  generally  used  of  such  consist- 
ence as  will  indent  readily  with  the  thumb-nail  when 
cold.  For  very  delicate  tissues,  saturation  in  a  mixture 
of  glycerin  and  gum  arabic,  made  perfectly  clear  and  vis- 
cid, so  as  to  be  easily  drawn  out  into  threads,  is  useful. 
After  saturation  the  specimen  is  thrown  into  alcohol, 
which  hardens  the  gum  and  fixes  the  tissues  so  as  to  be 
readily  cut.  The  thin  section  can  be  thrown  into  water, 
or  carmine  solution,  to  dissolve  the  gum,  and  the  stained 


228  THE    MICROSCOPIST. 

preparation  can  be  mounted  in  glycerin,  balsam,  or  dam- 
mar (Chapter  YI).  In  fixing  the  cover  to  specimens 
mounted  in  glycerin  it  may  be  useful  to  apply  liquid  glue 
or  strong  gelatin  solution  to  the  edges,  using  the  turn- 
table or  otherwise,  and  after  it  is  dry  to  cover  it  with 
some  other  cement.  Any  glycerin  which  may  accident- 
ally be  on  the  cover  had  better  be  left  until  the  glue  has 
dried,  when  it  can  be  removed  by  a  camel's  hairbrush  and 
water. 

Dr.  Beale  recommends  that  nitrate  of  silver,  chloride 
of  gold,  osmic  acid,  etc.,  when  used  for  staining  fine  tis- 
sues, should  be  dissolved  in  glycerin.  Less  than  J  per 
cent,  solution  of  gold,  etc  ,  will  thus  bring  out  details 
which  are  scarcely  attained  otherwise.  The  time  of  soak- 
ing and  strength  of  the  solution  varies  according  to  the 
tissue  and  effect  desired. 

The  most  delicate  sections  are  made  by  freezing  speci- 
mens after  they  have  been  well  saturated  with  a  strong 
solution  of  gum  arabic.  For  this  purpose  Professor 
Rutherford's  freezing  microtome  has  been  invented,  in 
which  the  cylinder  of  the  ordinary  section-cutter,  page 
63,  is  surrounded  by  a  reservoir  for  powdered  ice  and  salt, 
so  as  to  freeze  the  tissue.  Dr.  Beale  recommends  freez- 
ing by  the  use  of  nitrous  oxide  gas,  and  Dr.  Pritchard 
has  suggested  a  metallic  cylinder  with  a  wooden  handle, 
which  can  be  cooled  below  the  freezing-point  by  salt  and 
ice.  A  small  piece  of  tissue  will  immediately  freeze  on 
the  metal  so  as  to  be  cut  into  thin  sections  by  hand.  If 
thawing  sets  in  it  may  be  covered  with  thin  gutta-percha 
and  plunged  into  the  ice  and  salt. 

Dr.  S.  Marsh,  in  an  excellent  little  treatise  on  section- 
cutting,  recommends  that  the  knife  should  not  be  ground 
flat  on  one  side,  but  be  slightly  concave  on  each  side.  In 
cutting  it  is  necessary  to  keep  the  blade  well  flooded  with 
spirit,  except  in  using  the  freezing  microtome.  The  sec- 
tions are  best  transferred  to  a  basin  of  water,  and  lifted 


THE    MICROSCOPE    IN    PATHOLOGY.  229 

to  the  staining  fluid,  etc.,  not  with  a  camel's  hair  brush, 
but  with  a  little  slip  of  tin,  copper,  etc.,  with  a  bent  and 
perforated  end,  making  a  sort  of  lifter  or  flat  spoon.  In 
making  sections,  either  by  hand  or  with  the  section-cut- 
ter, the  razor  or  knife  must  be  kept  always  sharp,  and 
drawn  from  heel  to  point  so  as  to  cut  with  a  single  stroke 
the  thinnest  possible  slice. 

THE    APPEARANCE   OF    TISSUES    AFTER    DEATH. 

Formation  and  decomposition,  or  progression  and  retro- 
gression, coexist  in  most  morbid  structures,  so  that  it  is 
necessary  for  the  student  not  only  to  be  familiar  with 
normal  histology,  but  also  with  the  products  of  decay  and 
death  and  the  varied  appearances  in  disease. 

The  death  of  the  individual  parts  of  the  organism  is 
called  necrosis,  mortification,  or  gangrene.  Various  changes 
follow  it,  depending  chiefly  on  moisture,  producing  dry  or 
moist  gangrene. 

Necrosis  depends  on  the  cessation  of  the  nutritive  pro 
cess  from  abolition  of  the  normal  supply  of  blood,  or  from 
mechanical  or  chemical  violence. 

Living  tissues  bathed  in  suitable  fluids  dissolve  albumi- 
nates  and  their  derivatives,  but  when  life  departs  they  no 
longer  withstand  solution  themselves. 

1.  Protoplasm. — It  has  been  shown,  page  118,  that  the 
term  bioplasm  has  been  appropriated  to  elementary  or 
germinal  structure  during  life,  and  at  page  188  we  re- 
garded the  leucocytes,  or  white  corpuscles  of  the  blood, 
chyle,  etc.,  as  simply  bioplasts.     After  death,  or  in  order 
to  designate  their  physical  constitution,  the  most  suitable 
term  for  them  is  protoplasm.     In  necrosis  this  colorless 
protoplasm  dissolves  after  slightly  swelling,  and  entirely 
disappears. 

2.  Blood. — Decomposes    very   rapidly.      The   coloring 
matter  leaves  the  red  corpuscles  and  is  diffused  through 


230 


THE    MICROSCOPIST. 


FIG.  182. 


the  tissues  (hence  the  dark  color  of  a  scab),  then  the  cor- 
puscle disintegrates  and  breaks  up  into  granules.  Some- 
times there  is  found  an  aggregation  of  brownish-colored 
blood-corpuscles  undergoing  disintegration  at  the  edges  as 
in  Fig.  ]  82. 

3.  Nucleated  Cells.— In  these  the 
protoplasm  coagulates,  forming  a 
solid  albuminate,  which  becomes 
cloudy  and  breaks  up  into  gran- 
ules. 

4.  Cell  membrane    resists     de- 
composition in  proportion  as  it 
has  become  horny.      Hence  the 
outer  layers  of  epithelium   last 
longer  than  the  inner  ones. 

The  gangrenous  disintegration  of         5"    Smooth      MuSOldar     Fibre.— 

tissues,  a.  Aggregation  of  biood-cor- Minute  dusty  granulations  first 

puscles.    6.  Smooth   muscular  fibres.  ,  . 

c.  striated  muwuiar  fibres.  &  Break- make   their   appearance,   which 

ing  up  of  same  into  Bowman's  disks.  unite  go  t^at  t]ie  f^re  Seems 
1-300.— After  EINDFLEISCH. 

transversely  striated.    As  decay 

goes  on  the  muscle  changes  into  a  slimy  granular  substance 
which  may  be  drawn  into  threads. 

6.  Striated   Muscular   Fibre. — The   muscle-juice  coagu- 
lates to  a  solid  albuminate,  giving  rise  to  rigor  mortis  in 
from  twelve  to  fourteen  hours  after  death,  except  in  death 
from  charcoal  or  sulphuretted  hydrogen  vapor,  lightning, 
or  from  putrid  fevers,  or  long  debility.     This  stiffness  of 
muscle  lasts  about  twenty-four  hours.     In  the  necrosed 
fibres  under  the  microscope  the  transverse  striae  and  nu- 
clei disappear  amid  a  cloud  of  minute  granulations,  then 
fat-globules   and   reddish   pigment-granules   show  them- 
selves, the  fibres  melt  away  from  the  edges  and  become 
gelatinous.     If  gelatinous  softening  is  marked  the  fibres 
may  disintegrate  into  Bowman's  disks,  or  disks  produced 
by  transverse  cleavage  (Fig.  182). 

7.  Nerve-tissue. — Little  is  known  of  the  process  of  de- 


THE    MICROSCOPE    IN    PATHOLOGY. 


231 


FIG.  183. 


cay  in  nerves  save  that  the  thicker  nerve-trunks  maintain 
themselves  for  a  comparatively  long  time,  while  the  finer 
ramifications  soon  dissolve.  The  white  substance  of 
Schwann  (page  199)  first  coagulates,  then  there  is  a  col- 
lection of  drops  of  myelin  within  the  neurilemma,  produc- 
ing varicosity  before  complete  dissolution. 

8.  Adipose  Tissue. — The  fluid  fat  leaves  the  cells  and 
gives  an  appearance  of  emulsion  to  the  mass.    Crystals  of 
margarin,  etc.,  sometimes  appear  on  the  cell-walls. 

9.  Loose  connective  tissue  fibres  swell,   become  stained 
with  the  coloring  matter  of  blood,  granulate,  and  liquefy  ; 
or  they  may  desiccate  by  evaporation. 

10.  Elastic    fibres     and    fi- 
brous  networks    resist    longer 
than  the  last.     Hence,  elastic 
fibres  may  be  found  in  expec- 
torated  matter  from    gangre- 
nous lungs,  etc.      Later  they 
break  into  granular  strise,  then 
into  molecules  and  vanish. 

11.  Cartilage  lasts  long,  but 
melts  away  at  the  edges,  first 
becoming  transparent  and  red- 
dish.    The  cells  fill  with  fat- 
globules  from  fatty  degenera- 
tion of  the  bioplasm. 

12.  Bone    retains   its  struc- 
ture long,  so  as  to  be  recog- 
nized by  the  surgeon  in  seques- 
trse,  yet  it  decays  in  patches. 
The  bioplasm  changes  to   fat 
in  the  cells,  acid  fluids  dissolve 

the  lime  salts,  and  the  remaining  structure  disintegrates 
like  cartilage. 

The  chemical  products  of  decomposition  are  but  par- 
tially known.       Some  are  volatile,  some  soluble  in  water, 


Products  of  gangrenous  disintegra- 
tion, a.  Leucin  ;  6.  Tyrosin;  c.  Fat- 
crystals  ;  d.  Ammoniaco-magnesian 
phosphate ;  e.  Gangrene  particles  (blacfe 
pigment);/.  Vibriones.  1-300,— After 

KlNDFLEISCH. 


232  THE    MICROSCOPIST. 

and  others  more  solid,  producing  a  new  series  of  micro- 
scopic objects  after  the  disappearance  of  the  histological 
forms  (Fig.  183). 

Leucin  (Fig.  183,  a)  forms  partly  homogeneous  drops 
or  globules,  partly  bodies  of  concentric  layers,  and  partly 
stellate  spheres  of  minute  crystalline  needles. 

Tyrosin  (b)  generally  found  along  with  leucin,  forms 
satiny  white  needles,  isolated,  or  in  sheafs  or  rosettes. 

Margarin  (c)  a  mixture  and  crystalline  separation  of 
the  solid  fats,  stearin,  and  palmitin,  occurs  quite  fre- 
quently. 

Ammoniaco-magnesian  phosphate  (d)  is  only  found  in 
alkaline  or  neutral  ichor. 

Pigment-bodies  (e)  are  very  small,  and  have  a  variety  of 
forms.  As  characteristic  of  necrosis  the  small,  black, 
irregular  particles,  resisting  most  reagents,  must  be  dis- 
tinguished from  hsematin  pigments,  though  they  are 
probably  identical  with  melalin. 

Living  Organisms  (/). — In  addition  to  minute  fungi,  or 
moulds  (aspergillus,  oidium,  etc.),  vibriones  are  quite  com- 
mon. Pasteur  regards  them  as  the  visible  elements  of 
decay  (see  page  135). 

DEGENERATION   OF    TISSUES. 

Degenerations  are  usually  divided  into  two  classes,  true 
degenerations,  or  metamorphoses,  and  the  infiltrations. 

1.  The  true  degenerations  or  metamorphoses  are  char- 
acterized by  the  direct  change  of  the  albuminoid  constitu- 
ents of   the  tissues  into  new  material.     The  metamor- 
phoses include  fatty,  mucoid,  and  colloid  degenerations. 

2.  The  infiltrations  differ  from  the  true  degenerations, 
since  the  new  material  which  exists  in  the  tissues  is  not 
derived  from   their   albuminoid  constituents,  but  is  de- 
posited in  them  from  the  blood.     The  anatomical  char- 
acters are  much  less  altered  than  in  the  metamorphoses, 


THE    MICROSCOPE    IN    PATHOLOGY. 


233 


FIG.  184. 


and  function  is  usually  less  interfered  with.  They  include 
fatty,  amyloid,  calcareous,  and  pigmentary  infiltration,  etc. 

THE   METAMORPHOSES. 

1.  Fatty  Degeneration. 

The  metamorphosis  of  the  protoplasm  of  the  cell  is 
marked  by  the  occurrence  of  fat- 
globules  in  its  interior.  Its  pro- 
gress may  be  illustrated  by  de- 
generating epitheliun  in  dropsy 
of  the  pericardium  (Fig.  184). 

The  granular  corpuscles  were 
formerly  known  as  the  "  inflam- 
matory "  or  u  exudation  corpus- 
cles," or  "  corpuscles  of  Gluge." 
They  are  identical  in  structure 
with  colostrum-corpuscles  thrown 
off  by  the  mammary  gland  after 
parturition,  and  the  last  act  of 
fatty  degeneration  is  considered 

as  a  lactification.  The  fatty  detritus  may  be  absorbed  as 
milk,  or  if  not  absorbed  it  is  partly  saponified  and  partly 
separated  in  solid  form,  as  margarin,  etc.  Finally  there  is 
an  abundant  deposition  of  crystals  of  cholesterin  (Fig.  185). 

This  substance  is  found  nor- 
mally in  the  brain  and  spinal 
marrow  in  quite  large  propor- 
tions, and  in  solution  in  the 
bile.  It  forms  rhombic  tablets, 
lying  in  heaps,  with  their  long 
sides  parallel. 

In  some  cases  when  the  fatty 
detritus  is  not  absorbed  it 
undergoes  a  change  into  a 
crumbling  material  somewhat 
resembling  cheese,  and  hence  called  'caseation.  This  ap- 


The  fatty  metamorphosis.  Epi- 
thelium of  the  pericardium  in 
dropsy  of  pericardium,  a.  Cells 
which  still  show  the  normal  form 
and  arrangement.  First  appear- 
ance of  fat-globules,  b.  Granular 
globules,  the  one  with  a  nucleus 
still  visible,  c.  Granular  globules 
disintegrating  to  fatty  detritus. — 
After  KINDFLEISCH. 


FIG.  185. 


Crystals  of    cholesterin.— After  VIR- 
cuow. 


234 


THE    MICROSCOPIST. 


pears  to  be  owing  to  desiccation  of  the  substance  from  de- 
ficient vascular  supply.  It  is  most  frequent  in  parts  which 
contain  but  few  vessels,  or  in  those  in  which  the  vessels 
are  obliterated  by  new  growths.  It  was  formerly  believed 
to  be  the  product  of  tuberculosis,  and  regarded  as  the 
separation  of  morbid  matter  (crude  tubercle)  from  dis- 
eased blood.  Tubercle  may  undergo  fatty  degeneration 
and  caseation,  but  it  is  by  no  means  true  that  all  cheesy 
masses  are  tubercular. 

Fatty  degeneration  in  the  arteries  may  be  illustrated 
by  atheroma,  beginning  as  a  fatty  metamorphosis  of  con- 
nective tissue,  and  ending  in  calcification  or  impregnation 
with  lime  salts.  In  the  fibres  of  voluntary  muscle  the  al- 
buminous matter  of  the  fibre  is  converted  into  fat,  which 
is  seen  in  rows  of  minute  globules,  like  strings  of  pearls 
in  the  long  axis  of  the  primitive  bundles,  while  the  trans- 
verse striae  become  indistinct  (Fig.  186). 

In  advanced  stages  of  infantile  spinal 
paralysis,  perhaps  from  inaction  as  well 
as  innutrition,  the  atrophied  muscles  are 
subject  to  fatty  degeneration,  which  may 
be  observed  by  removing  small  portions 
of  muscular  tissue  by  Duchenne's  trocar, 
a  sort  of  double  needle,  one  part  of  which 
slides  upon  the  other,  jutting  against  a 
steel  shoulder,  so  as  to  catch  and  detach 
a  small  piece  from  a  muscle  into  which  it 
is  inserted.  A  microscopic  examination 
of  the  detached  fibre  will  show  the 
amount  of  degeneration,  and  thus  from 
time  to  time  the  progress  of  disease  or 
the  effects  of  treatment  may  be  noted. 

In  pulmonary  emphysema  the  epithe- 
lium is  so  changed  by  fatty  degeneration 
that  the  degenerated  elements  are  better 


FIG.  186. 


Fatty  degeneration 
of  striated  muscular 
fibres.  1-300.— After 

RlNDFLEISCH. 


seen  than  the  normal  (Fig.  187). 


TUB    MICROSCOPE    IN    PATHOLOGY. 


235 


Softening  of  the  brain,  as  it  is  termed,  is  largely  due  to 
fatty  degeneration.  Whatever  interferes  with  nutrition, 
by  preventing  a  proper  supply  of  blood,  will  produce  fatty 
degeneration  and  softening.  Acute  cases  may  be  pro- 
duced by  embolism  or  thrombosis.  White  softening  is 
generally  a  chronic  condition  of  old  age,  and  owes  its 


FIG. 187. 


From  the  inner  surface  of  a  larger  emphysema  vesicle.  Fatty  remains  of  the  lung- 
tissue,  containing  elastic  fibres,  smooth  muscular  fibres,  and  covered  with  fatty  degen- 
erated epithelia.  1-500. — After  RINDFLEISCH. 

color  to  the  gradual  diminution  of  blood-supply.  Yellow 
and  red  softening  depend  on  larger  proportions  of  blood- 
pigments.  A  vertical  section  of  a  specimen  of  yellow 
softening  shows  accumulations  of  fatty  granules  between 
the  nerve-fibres,  and  their  formation  into  larger  granular 
corpuscles  (Fig.  188). 

2.  Mucoid  Degeneration. 

This  is  a   transformation  of  albuminoid   tissues  into 
mucin,  a  material  of  a  soft  jellylike  consistence.     This  is 


236 


THE    MICROSCOPIST. 


the  embryonic  condition  of  most  tissues,  and  in  the  um- 
bilicus and  the  vitreous  humor  of  the  eye  this  character 
persists  after  birth. 

The  mucus  which  normally  covers  the  mucous  mem- 
branes is  largely,  if  not  wholly,  derived  from  the  swell- 
ing and  softening  of  epithelial  cells,  but  in  mucoid  degen- 


FIG.  188. 


Yellow  softening  of  the  white  substance  of  the  brain.  A.  Border  of  the  depot  of  soft- 
ening, S,  and  of  the  brain-substance,  C,  not  yet  softened.  D.  A  fatty  degenerated  ves- 
sel. 1-300.— After  RINDFLEISCH. 

eration  the  change  chiefly  pertains   to  the  intercellular 
elements.     Thus  cartilage  softens  (Fig.  189). 

The  matrix  first  exhibits  strise  which  afterwards  split 
into  fibres.  The  ends  of  the  fibrils  taper  to  a  point  and 
are  dissolved  by  mucoid  metamorphosis.  In  bone  the 
solution  of  the  lime  salts  and  the  liquefaction  of  the  basis- 
substance  are  generally  simultaneous,  but  in  some  cases, 
as  in  Fig.  190,  the  difference  between?  the  two  is  quite 
apparent. 

3.  Colloid  Degeneration. 

In  this  the  cells,  rather  than  the  intercellular  structure, 
are  especially  involved.  Colloid  resembles  mucin  in  ap- 


THE    MICROSCOPE    IN    PATHOLOGY.  237 

pearance,  but  unlike  it  contains  sulphur  and  is  precipi- 


FIG. 189. 


Softening  of  cartilage.    Vertical  section  of  an  articular  cartilage  in  malum  senile  ar- 
ticulorum.    1-300.— After  RINDFLEISCH. 

FIG.  190. 


Softening  of  bone.  Fragment  of  bone  from  the  spongy  substance  of  an  osteomala- 
cious  rib.  a.  Normal  osseous  tissue ;  6.  Decalcified  osseous  tissue  ;  c.  Haversian  canals ; 
d.  Medullary  spaces;  d*.  A  medullary  space  filled  with  red  medulla.  1-300.— After 
RINDFLEISCH. 


238 


THE    MICROSCOPIST. 


tated  by  acetic 

FIG. 191. 


Colloid  degenerat- 
ing cells  from  a  colloid 
cancer  — After  RIND- 

FLEISCH. 


acid.  It  resembles  jelly  or  half-set  glue. 
It  first  appears  as  a  small  globule  in  the 
cell,  which  grows,  pushing  aside  the  nu- 
cleus, until  it  not  only  fills  the  cell  but 
swells  largely ,  communicating  with  neigh- 
boring cells  so  as  to  form  cystlike  cavi- 
ties containing  the  gelatinous  substance. 
Here  it  may  afterwards  undergo  lique- 
faction (Fig.  191). 

The  colloid  change  is  most  common  in 
enlargements  of  the  thyroid  gland,  in  the 
lymphatic  glands,  and  in  many  of  the 
new  formations.  Colloid  or  mucoid  tu- 
mors, or  tumors  which  have  undergone 
these  forms  of  transformation,  are  some- 


FIG.  192. 


Colloid  degeneration  in  the  stronia  of  an  ovarian  cystoid.  a,  a.  Larger  cysts,  whose 
walls  bear  an  incomplete  epithelium  of  low  cylindrical  cells  whose  contents  after  hard- 
ening is  split  up  radiating.  6.  Younger  cysts  without  epithelium  permeated  by  remains 
of  connective  tissue  fibres,  c.  The  same  with  a  wreath  of  loose  epithelia  d.  Colloid 
infiltration  of  the  connective  tissue  which  has  not  yet  attained  any  cystoid  appearance 
and  inclosure.  «.  Small-celled  infiltration  of  the  stroma.  1-200.— After  EINDFLEISCH. 


THE    MICROSCOPE    IN    PATHOLOGY.  239 

times  called  colloid  cancers,  when  their  structure  may  be 
altogether  different  from  cancer. 

Some  forms  of  multilocular  ovarian  cysts  depend,  ac- 
cording to  Rindfleisch,  upon  a  colloid  degeneration  of  the 
stroma  of  the  ovary,  wherein  an  epithelial  proliferation 
furnishes  the  foundations  of  the  cysts.  Such  a  case  may 
be  termed  a  cystic  colloid  cancer  of  the  ovary  (Fig.  192). 

THE   INFILTRATIONS. 

1.  Amyloid  Infiltration. 

This  is  known  also  as  lardaceous  or  waxy  degeneration 
and  vitreous  swelling.  It  consists  of  the  infiltration  of 
some  sort  of  albuminate  from  the  blood,  which  is  charac- 
terized by  its  becoming  brownish-red  or  violet  color  by 
treatment  with  iodine.  It  sometimes  exhibits  concentric 
layers,  like  starch,  which  with  the  color  phenomena  led 
Virchow  to  call  it  amyloid. 

The  amyloid  infiltrated  cell  (Fig.  193)  is  distinguished 
from  the  normal  by  its  greater  circumference,  together 

FIG  193 


Amyloid  infiltrated  liver-cells,  a.  Isolated  cells,  b.  A  fragment  of  the  liver-cell  net- 
work, in  which  the  dividing  lines  of  the  individual  cells  are  no  longer  visible.  1-300. 
—After  RINDFLEISCH. 

with  a  certain  rounded  irregularity.  If  several  are  in 
contact  they  often  coalesce  into  elongated  lumps,  in  which 
the  individual  elements  connot  be  recognized. 

The  walls  of  small  arteries  and  capillaries  are  the  first 
to  be  attacked  in  all  infiltrations,  and  this  is  especially 
observable  in  amyloid  infiltration.  Fig.  194  represents 
partial  amyloid  infiltration  of  a  Malpighian  tuft  of  the 
kidney.  The  blue  injection,  and  of  course  the  blood  dur- 


240 


THE    MICROSCOPIST. 


ing  life,  penetrates  only  the  capillary  loops  which  are  free 
from  deposit.  The  addition  of  iodine,  staining  the  amy- 
loid matter  red,  gives  an  alternation  of  blue  and  red  loops. 


FIG.  194. 


Amyloid  infiltrated  Malpighian  vascular  coil  of  the  kidney.  1-300.— After  RINDFLEISCH. 

Amyloid  infiltration  impairs  the  nutrition  of  a  part 
both  by  the  obstruction  of  the  circulation  and  by  its 
direct  influence.  Hence  atrophy  and  fatty  metamorphosis 
are  often  found  associated  with  it. 

In  lardaceous  liver,  or  amyloid  infiltration  of  the  liver, 
the  minute  branches  of  the  hepatic  artery  are  first  affected, 
then  the  region  of  the  hepatic  vein,  and  afterwards  the 

FIG.  195. 


Amyloid  liver.  A.  Interlobular  artery  with  amyloid  walls.  G,  G.  Biliary  ducts. 
p,p.  Portal  vessels.  V,  V.  Interlobular  veins.  The  liver-cells  in  the  central  zones  of 
the  acini  are  infiltrated  with  amyloid  substance.  1-300.— After  BINDFLEISCH. 


THE    MICROSCOPE    IN    PATHOLOGY. 


241 


hepatic  cells  in  the  region  of  the  portal  vein,  until  the 
whole  organ  may  ultimately  have  twice  as  much  solid 
albuminous  substance  as  normal,  and  becomes  pale  gray 
in  color,  translucent,  and  of  vvaxlike  consistence  (Fig.  195). 

2.   Calcification. 

Calcification  is  the  infiltration  of  tissue  with  solid  phos- 
phate or  carbonate  of  lirne.  Free  carbonic  acid  is  solvent 
of  these  salts,  and  by  its  capacity  for  diffusion  it  escapes, 
leaving  the  insoluble  salts  in  the  nutritive  fluid. 

Thus  cartilage  normally  becomes  bone,  and  under  pecu- 
liar circumstances  other  tissues  ossify.  True  osseous  tis- 
sue, however,  differs  greatly  from  mere  calcification  by 


FIG.  I9fi. 


Arthritis  uratica.  Vertical  section  through  a  superficial  articular  body  infiltrated  with 
urate  of  lime.  a.  The  surface.  6.  Cartilage  cavities  with  tufts  of  crystals,  c.  Cartilage 
cells  not  yet  infiltrated,  in  division,  d.  Isolated  needles  of  crystals  in  the  basis-substance. 
— After  CORNEIL  ET  EANVIER. 

the  arrangement  of  its  solid  particles  (see  page  195). 
Calcification  of  arteries  is  a  secondary  affection,  succeed- 
ing to  fatty  degeneration  of  the  connective  tissue. 

Analogous  to  calcification   is   the  arthritic  deposit  of 

16 


242 


THE    MICROSCOPIST. 


FIG.  197. 


urates  into  articular  cavities,  and  the  parenchyma  of  the 
cartilage,  bones,  and  membranes  of  the  joints  of  gouty 
persons.  It  is  most  common  in  the  cartilage  cells  (Fig. 
196). 

The  uric  acid  infiltration  acts  as  a  mechanico-chemical 
agent  to  the  affected  parts,  producing  oedema,  suppura- 
tion, caries,  etc. 

3.  Pigmentation. 

All  true  pigments  are  derived  from  the  coloring  matter 
of  the  blood.  Many  of  them  are  elimi- 
nated by  the  kidneys  and  liver,  but  some 
are  deposited  in  the  tissues,  as  the  choroid 
coat  of  the  eye  and  the  rete  Malpighii  of 
the  skin.  Some  pathological  cases  may 
be  ascribed  to  extravasation  or  some  local 
stasis  in  the  circulation ;  others  may  be 
caused  by  wandering  leucocytes  (page 
188).  The  brown  atrophy  of  the  muscu- 
lar tissue  of  the  heart,  which  is  often  as- 
sociated with  marasmus,  is  caused  by  the 
deposit  of  yellow  granular  pigment  in  the 
muscular  fibre  (Fig.  197). 

The  dark  pigment  of  the  lungs  owes 
its  origin  chiefly  to  the  respiration  of 
carbon  in  the  shape  of  particles  of  soot, 
coal-dust,  etc.,  floating  in  the  atmosphere.  These  parti- 
cles are  first  taken  up  by  the  mucous  corpuscles  (leuco- 
cytes) of  the  trachea  and  bronchi,  and  many  of  them  are 
expectorated.  Some,  however,  make  their  way  to  the 
air-vesicles,  and  penetrate  the  alveolar  walls  and  inter- 
lobular  tissue  (Fig.  198). 

In  the  case  of  coal-miners  the  lungs  often  become  uni- 
formly black.  Workers  in  iron-dust  are  liable  to  have 
the  lungs  stained  red  from  oxide  of  iron,  and  stonecutters, 
etc.,  to  inhale  and  deposit  silicic  acid  or  fine  sand.  Such 


Brown  atrophy  of 
heart-muscle.  Frag- 
ment of  a  membrane 
of  muscular  fibres, 
with  pigment-gran- 
ules in  the  interior 
of  the  primitive  bun- 
dles. 1-300.  —  After 

RlNDFLEISCH. 


THE    MICROSCOPE    IN    PATHOLOGY. 


243 


particles  produce  irritation  and  inflammatory  phenomena, 
accompanying  which  is  a  formation  of  true  pigment  from 
the  blood,  whose  deposit  increases  the  darkness  of  tint  in 


FIG.  198. 


FIG.  199. 


Anthracosis.     Coal-dust   inhaled  into  the  alveolar  septa  of  the  lung.     1-3)0.— After 

ElNDFLEISCH. 

the  lungs.     Many  morbid  conditions,  also,  are  attended 
with  formation  of  pigment. 

4.  Fatty  Infiltration. 

In  this  form  of  degeneration  the  fat  is  derived  from  the 
food,  and  must  be  distinguished  from 
that  metamorphosis  called  fatty  degen- 
eration. In  fatty  infiltration  the  fat 
occurs  in  the  cells  as  distinct  drops  of 
oil  (Fig.  199). 

The  vitality  and  functions  of  the  cells 
are  but  little  impaired  by  the^ accumu- 
lation, which  may  be  again  reabsorbed, 
while  in  fatty  metamorphosis  the  ele- 
ments are  destroyed.  Fatty  infiltra- 
tion of  muscle  is  seen  in  the  connective 
tissue  between  the  fasciculi,  and  not  in 
the  muscular  fibres  themselves  as  in  fatty  degeneration. 


Fatty  infiltrated  liver- 
cells.         1-300.  —  After 

RlNDFLEISCH. 


244 


THE    MICROSCOPIST. 


The  "  fatty  liver,"  as  it  is  called,  is  due  to  infiltration. 
The  ingestion  of  fatty  aliments  is  followed  by  temporary 
accumulation  of  fat  in  the  portal  blood,  which  is  apt  to  be 
deposited  in  the  portal  capillaries  of  the  liver,  which  is 
gradually  conveyed  to  the  central  or  hepatic  capillaries  of 
the  lobules,  and  thus  to  the  general  circulation.  In  mor- 
bid conditions,  as  in  tuberculosis  and  heart  disease,  we 
find  the  morbidly  fatty  liver  first  infiltrated  in  the  portal 
zone  as  in  Fig.  200. 


FIG.  200. 


Fatty  liver  of  moderate  degree,  serai-diagrammatic.  V.  Lumina  of  the  central  veins. 
p.  Interlobular  branches  of  the  vena  portae.  A.  Arterial  branches.  G.  Biliary  ducts. — 
After  RINDFLEISCH. 

In  more  advanced  cases  all  the  liver-cells  become  filled 
and  the  bounds  of  the  acini  are  effaced.  Fat  may  occur 
in  the  liver  in  connection  with  general  obesity,  or  from  a 
failure  of  the  oxygenating  power  of  the  blood,  in  which 
case  there  may  be  general  emaciation. 


5.  Albuminous  Infiltration. 

Albuminous  infiltration,  or  cloudy  swelling,  consists  in 
filling  the  tissues  with  molecular  albumen.  It  is  regarded 
by  Virchow  as  a  nutritive  irritation,  or  an  in  citation  of 


THE    MICROSCOPE    IN    PATHOLOGY. 


245 


cells  to  take  up  an  abnormal  amount  of  nutritive  mate- 
rial. It  occurs  after  local  and  general  irritations,  which 
bring  to  the  part  an  increased  supply  of  blood,  and  is  es- 
pecially important  in  the  muscles  and  the  large  glands,  as 
the  liver  and  kidneys.  In  the  latter  it  is  often  associated 
with  fatty  degeneration  and  fibrinous  exudation,  as  in 
Fig.  201. 

FIG. 201. 


1.  Cloudy  swelling  and  commencing  fatty  degeneration  of  the  epithelia  of  the  convo- 
luted urinary  tubuli.  2.  Advanced  fatty  degeneration.  3.  Formation  of  fibrinous  cyl- 
inders, a.  Cross-cut  of  a  urinary  tubulus,  with  a  gelatinous  cylinder  filling  the  lumen. 
b.  Epithelium,  c.  Tunica  propria.  d.  Renewed  production  of  colloid  at  the  surface  of 
the  epithelial  cells,  which  elevates  the  older.  1-500.— After  RINDFLEISCH. 


6.  Serous  Infiltration. 

This  is  an  infiltration  of  the  tissues  with  a  serous  or 
sero-mucous  substance  producing  oedema,  and  seems 
analogous  to  mucoid  degeneration.  Under  the  micro- 
scope bright  spots  appear  in  various  cells,  of  which  Wag- 
ner declares  it  to  be  uncertain  whether  they  are  artificial 
or  diseased  products,  and  if  the  latter,  whether  they  are 
serous,  mucous,  or  colloid. 


246  THE    MICROSCOPIST. 


INFLAMMATION. 

Inflammation  is  a  complex  process,  beginning  with  an 
increased  flow  of  blood  into  or  towards  the  part  affected, 
and  generally  leading  to  exudation  or  suppuration,  some- 
times healing  by  resolution  or  leading  to  new  formations, 
to  various  metamorphoses,  or  to  destruction  of  tissues, 
with  a  disturbance  of  the  function  of  the  part  affected. 

Inflammation  of  the  various  tissues  or  organs  are  dis- 
tinguished by  adding  the  termination  itis  to  the  Latin  or 
Greek  term,  as  encephalitis,  pleuritis,  nephritis,  etc. ;  or  a 
special  name  is  given,  as  pneumonia,  for  inflammation  of 
the  lungs,  erysipelas,  for  inflammation  of  the  skin,  etc. 

Inflammations  of  serous  coverings  of  organs  receive  the 
prefix  peri,  as  perihepatitis,  perimetritis,  etc.  (except  peri- 
bronchitis,  and  peri  phlebitis,  which  refer  to  inflammation 
of  the  exterior  of  the  bronchial  or  venous  wall).  Inflam- 
mations of  the  surrounding  connective  tissue  or  appen- 
dages of  an  organ  are  known  by  the  prefix  para,  as  para- 
nephritis,  paraeystitis,  parametritis,  etc. 

Inflammation  is  the  result  of  some  kind  of  injury  to 
the  tissue  affected,  either  direct,  as  from  mechanical  or 
chemical  agents,  or  indirect,  as  from  specific  contagions, 
exposure  to  cold,  etc. 

The  first  phenomenon  of  inflammation  is  congestive 
hypersemia,  or  an  increased  flow  of  blood.  There  is  first 
a  dilatation  of  the  vessels,  with  an  acceleration  of  the 
current,  which  is  soon  followed  by  a  retardation  of  the 
current,  producing  stagnation  or  cessation  of  circulation. 
Several  theories  have  been  advanced  to  explain  this  phe- 
nomenon. According  to  the  paralytic  theory  the  irrita- 
tion affects  only  the  sensitive  nerves,  e.  g.,  of  the  skin, 
and  produces  an  antagonistic  paralysis  in  the  vasomotor 
nerves.  The  vessels  then  relax,  dilate,  and  receive  more 
blood.  According  to  Virchow  and  Beale,  it  is  the  cell  in 


THE    MICROSCOPE    IN    PATHOLOGY. 


247 


itself  without  the  intervention  of  the  nerves  or  the  blood, 
which  is  excited  to  increased  nutritive  activity,  to  greater 
metamorphosis,  and  to  new  formation ;  and  the  more 
quickly  this  takes  place,  the  more  it  runs  the  danger  of  de- 
struction, the  more  is  the  process  to  be  looked  on  as  in- 
flammatory. There  may  be  truth  in  both  these  views, 
since  the  nutrition  of  the  cell  is  so  greatly  influenced  by 
nerve  action. 

The  second  phenomenon  of  inflammation  is  exudation 
and  suppuration.  The  most  disputed  point  respecting  in- 
flammation has  been  the  genesis  of  pus-corpuscles.  We 
have  seen,  page  189,  that  they  are  identical  in  the  living 
state  wuh  leucocytes,  or  white  blood-cells.  In  other  words, 
they  are  merely  particles  of  bioplasm.  Their  migration 

FIG.  202. 


Cohnheim's  experiment,    a.  Vein,    b  b.  Contiguous  connective  tissue,  permeated  by 
migrating  colorless  blood-corpuscles,    c.  Column  of  red  blood-corpuscles.    1-500.— After 

RlNDFLEISCH. 

through  the  walls  of  bloodvessels  was  first  described  by 
Dr.  Addison  in  1842,  and  afterwards,  in  1846,  by  Dr. 
Waller.  These  observations  w^ere  forgotten,  however,  un- 
til 1867,  when  Professor  Cohnheim,  of  Berlin,  showed  the 


248  THE    MICROSCOPIST. 

importance  of  this  migration  to  the  pathology  of  inflam- 
mation. His  experiment  consisted  in  stretching  the  mes- 
entery of  a  living  frog,  paralyzed  by  the  subcutaneous  in- 
jection of  I  per  cent,  solution  of  curare,  over  a  ring  of  cork, 
and  placing  it  under  the  microscope.  The  veins  are  seen  to 
dilate,  and  the  colorless  blood-corpuscles  first  cling  to  the 
inner  surface  of  the  wall  of  the  vessel,  then  a  process  from 
the  bioplast  passes  through  the  wall,  which  swells  up  out- 
side, and  in  this  wray  a  bridge  is  formed  upon  which  the 
whole  substance  of  the  cell  creeps  over.  By  their  amoeboid 
motions  the  cells  wander  further,  and  accumulate  at  the 
irritated  part  of  the  tissue  which  becomes  the  point  of  de- 
parture for  future  changes  (Fig.  202). 

Strieker  has  shown,  by  experiments  on  the  tongue  and 
cornea  of  the  frog,  that  the  migratory  cells,  or  pus-cor- 
puscles, in  inflammation  increase  by  division. 

Dr.  Beale  holds  the  opinion  that  although  some  of  the 
pus-corpuscles  may  be  derived  from  the  division  of  colorless 
blood-cells,  yet  the  great  mass  of  them  results  from  the 
bioplasts  of  the  tissues  in  which  the  pus-formation  takes 
place.  In  this  he  follows  the  earlier  teaching  of  Virchow, 
which  supplanted  the  older  view  that  pus-corpuscles  origi- 
nated in  a  structureless  exudation.  Dr.  Beale  recommends 
the  examination  of  a  portion  of  cuticle  raised  by  a  small 
blister,  which  may  be  stained  with  carmine,  or  examined 
fresh  in  the  serum  of  the  blister.  The  bioplasm  of  the 
inflamed  epithelial  cells  will  be  found  larger  than  in  the 
normal  state,  and  in  some  instances  will  be  seen  to  project 
beyond  the  formed  material  of  the  cells,  and  the  free 
portions  divide  and  subdivide  in  the  exudation  poured 
out  from  the  bloodvessels. 

In  Chapter  IX  we  have  referred  to  Dr.  Beale's  views 
respecting  the  elementary  histological  unit  or  cell,  which 
seem  to  agree  with  the  phenomena  recorded  by  Max 
Schultze,  Cohnheim,  Strieker,*  etc.  So  influential  have 

*  Strieker's  Manual  of  Histology,  chap.  i. 


THE    MICROSCOPE    IN    PATHOLOGY.  249 

been  these  views  in  pathology,  that  we  quote  from  him 
the  following  abstract  concerning  the  changes  in  the  cell 
in  disease : 

"  Of  the  different  constituents  of  the  fully  formed  cell, 
the  germinal  matter  is  alone  concerned  in  all  active 
change.  This  is,  in  fact,  the  only  portion  of  the  cell 
which  lives,  while  at  an  early  period  of  development  the 
parts  of  the  cell  usually  regarded  as  necessary  to  cell  ex- 
istence are  altogether  absent.  The  '  cell '  at  this  period 
is  but  a  mass  of  living  germinal  matter,  and  in  certain 
parts  of  the  body,  at  all  periods  of  life,  are  masses  of 
germinal  matter,  destitute  of  any  cell-wall,  and  exactly 
resembling  those  of  which  at  an  early  period  the  embryo 
is  entirely  composed.  White,  blood,  and  lymph  corpus- 
cles, chyle  corpuscles,  many  of  the  corpuscles  in  the  spleen, 
thy m us,  and  thyroid,  corpuscles  in  the  solitary  glands,  in 
the  villi,  some  of  those  upon  the  surface  of  mucous  mem- 
branes, and  minute  corpuscles  in  many  other  localities, 
consist  of  living  germinal  matter.  There  is  no  structure 
through  which  these  soft  living  particles  may  not  make 
their  way.  The  destruction  of  tissue  may  be  very  quickly 
effected  by  them,  and  there  is  no  operation  peculiar  to 
living  beings  in  which  germinal  or  living  matter  does  not 
take  part.  Any  sketch  of  the  structure  of  the  cell  would 
be  incomplete  without  an  account  of  some  of  the  essential 
alterations  which  take  place  in  disease,  and  it  is  therefore 
proposed  to  refer  very  briefly  to  the  general  nature  of 
some  of  the  most  important  morbid  changes. 

"If  the  conditions  under  which  cells  ordinarily  live  be 
modified  beyond  a  certain  limit,  a  morbid  change  may  re- 
sult. For  instance,  if  cells,  which  in  their  normal  state 
grow  slowly,  be  supplied  with  an  excess  of  nutrient  pabu- 
lum, and  increase  in  number  very  quickly,  a  morbid  state 
is  produced.  Or  if,  on  the  other  hand,  the  rate  at  which 
multiplication  takes  place  be  reduced  in  consequence  of 
an  insufficient  supply  of  nourishment,  or  from  other  causes, 


250  THE    MICROSCOPIST. 

a  diseased  state  may  result.  So  that,  in  the  great  majority 
of  cases,  disease,  or  the  morbid  state,  essentially  differs 
from  health,  or  the  healthy  state,  in  an  increased  or  re- 
duced rate  of  growth  and  multiplication  of  the  germinal 
matter  of  a  particular  tissue  or  organ.  In  the  process  of 
inflammation,  in  the  formation  of  inflammatory  products, 
as  lymph  and  pus,  in  the  production  of  tubercle  and  can- 
cer, we  see  the  results  of  increased  multiplication  of  the 
germinal  matter  of  the  tissues  or  of  that  derived  from  the 
blood.  In  the  shrinking,  and  hardening,  and  wasting 
which  occur  in  many  tissues  and  organs  in  disease,  we  see 
the  effects  of  the  germinal  matter  of  a  texture  being  sup- 
plied with  too  little  nutrient  pabulum,  in  consequence 
sometimes  of  an  alteration  of  the  pabulum  itself,  some- 
times of  an  undue  thickening  and  condensation  of  the 
tissue  which  forms  the  permeable  septum  intervening  be- 
tween the  pabulum  and  the  germinal  matter. 

"  The  above  observations  may  be  illustrated  by  reference 
to  what  takes  place  when  pus  is  formed  from  an  epithelial 
cell,  in  which  the  nutrition  of  the  germinal  matter,  and 
consequently  its  rate  of  growth,  is  much  increased.  And 
the  changes  which  occur  in  the  liver-cell  in  cases  of  cir- 
rhosis may  be  advanced  in  illustration  of  a  disease  which 
consists  essentially  in  the  occurrence  of  changes  more 
slowly  than  in  the  normal  condition,  consequent  upon  less 
than  the  normal  freedom  of  access  of  pabulum  to  the 
germinal  matter. 

"  The  outer  hardened  formed  material  of  an  epithelial 
cell  may  be  torn  or  ruptured  mechanically,  as  in  a  scratch 
or  prick  by  insects,  or  it  may  be  rendered  soft  and  more 
permeable  to  nutrient  pabulum  by  the  action  of  certain 
fluids  which  bathe  it.  In  either  case  it  is  clear  that  the 
access  of  pabulum  to  the  germinal  matter  is  facilitated,  and 
the  latter  necessarily  'grows' — that  is,  converts  certain 
of  the  constituents  of  the  pabulum  that  come  in  contact 
with  it  into  matter  like  itself  at  an  increased  rate.  The 


THE    MICROSCOPE    IN    PATHOLOGY.  251 

mass  of  germinal  matter  increases  in  size  and  soon  begins 
to  divide  into  smaller  portions.  Parts  seem  to  move  away 
from  the  general  mass.  These  at  length  become  detached, 
and  thus  several  separate  masses  of  germinal  matter, 
which  are  imbedded  in  the  softened  and  altered  formed 
material,  result.  In  this  way  the  so-called  inflammatory 
product  pus  results. 

"It  will  be  seen  how  easily  the  nature  of  the  changes 
occurring  in  cells  in  inflammation  can  be  explained  if  the 
artificial  nomenclature  of  cell-wall,  cell-contents,  nucleus 
be  given  up.  In  all  acute  internal  inflammations  a  much 
larger  quantity  of  inanimate  pabulum  is  taken  up  by  cer- 
tain cells  and  converted  into  living  matter  than  in  the 
normal  state.  Hence  there  is  increase  in  bulk;  cells  of 
particular  organs,  wrhich  live  slowly  in  health,  live  very 
fast  in  certain  forms  of  disease.  More  pabulum  reaches 
them,  and  they  grow  -more  rapidly  in  consequence. 

"In  cells  which  have  been  growing  very  rapidly  and 
are  returning  to  their  normal  condition,  in  which  the  access 
of  nutrient  pabulum  is  more  restricted  than  in  the  abnormal 
state,  as  is  the  case  in  normal  cells  passing  from  the  em- 
bryonic to  the  fully  formed  state,  the  outer  part  of  the 
germinal  matter  undergoes  conversion  into  formed  mate- 
rial, and  this  last  increases  as  the  supply  of  pabulum  be- 
comes reduced. 

"  We  will  now  inquire  what  alterations  can  be  observed 
in  cells,  the  ''formed  material'  of  which,  under  normal  con- 
ditions, becomes  quickly  resolved  into  other  soluble  con- 
stituents if  these  cells  be  placed  under  circumstances 
which  caused  the  formed  material  to  become  harder  and 
less  permeable  to  nutrient  matter  than  in  health.  The 
formed  material  which  enters  into  the  formation  of  the 
liver-' cell'  is  soft,  moist,  and  readily  permeable  to  certain 
nutrient  matters.  There  is  no  cell-wall,  but  the  outer 
part  of  the  formed  material  is  gradually  resolved  into 
soluble  biliary  matters,  which  pass  down  the  ducts,  and 


252  THE    MICROSCOPIST. 

• 

into  amyloid  and  saccharine  matters,  which  permeate  the 
walls  of  the  vessels  and  enter  the  blood.  To  make  up  for 
the  disintegration  of  the  outer  part  of  the  formed  mate- 
rial, new  formed  material  is  produced  in  the  interior  of 
the  cell  from  the  germinal  matter,  and  the  germinal  mat- 
ter which  undergoes  this  change  is  replaced  by  new  germi- 
nal matter  produced  from  the  pabulum  that  is  absorbed. 
If  such  cells  and  their  descendants  are  bathed  with  im- 
proper pabulum,  and  especially  with  substances  which 
render  albuminous  matters  insoluble,  or  possess  the  prop- 
erty of  hardening  them  (as  alcohol),  they  necessarily  di- 
minish in  size,  in  consequence  of  the  formed  material  be- 
coming less  permeable,  less  nutrient  matter  is  taken  up; 
and,  of  course,  as  the  formed  material  becomes  hardened, 
less  disintegration  takes  place,  the  quantity  of  secretion, 
which  really  consists  of  the  products  resulting  from  dis- 
integration, is  much  diminished,  and  the  amount  of  work 
performed  by  the  cell  is  reduced.  Under  the  supposed 
conditions  the  cells  shrink  in  size  and  become  more  firm 
in  texture.  Many  gradually  waste,  and  not  a  few  die, 
and  at  length  disappear.  These  seem  to  be  the  essential 
changes  which  slowly  take  place  in  the  liver-cells  in  cir- 
rhosis, and  to  these  changes  in  the  cells  the  striking 
shrinking  and  condensation  of  the  whole  liver,  so  charac- 
teristic of  this  disease,  are  due. 

"  From  these  observations  it  follows  that  disease  may 
result  in  two  wrays — either  from  the  cells  of  an  organ 
growing  and  multiplying  faster  than  in  the  normal  state, 
or  more  slowly.  In  the  one  case  the  normal  restrictions 
under  which  growth  takes  place  are  diminished ;  in  the 
other  the  restrictions  are  greatly  increased.  Pneumonia, 
or  inflammation  of  the  lung,  may  be  adduced  as  a  strik- 
ing example  of  the  first  condition,  for  in  this  disease  mil- 
lions of  cells  are  very  rapidly  produced  in  the  air-cells  of 
the  lung,  and  nutrient  constituents  are  diverted  from 
other  parts  of  the  body  to  this  focus  of  morbid  activity. 


THE    MICROSCOPE    IN    PATHOLOGY.  253 

Contraction  and  condensation  of  the  liver,  kidney,  and 
other  glands,  hardening,  shrinking,  and  wasting  the  mus- 
cular, nervous,  and  other  tissues,  are  good  examples  of 
the  second.  The  amount  of  change  becomes  less  and  less 
as  the  morbid  state  advances,  the  whole  organ  wastes, 
and  the  secreting  structure  shrinks,  and  at  last  inactive 
connective  tissue  alone  marks  the  seat  where  most  active 
and  energetic  changes  once  occurred.  It  is  easy  to  see 
how  such  a  substance  as  alcohol  must  tend  to  restrict  the 
rapid  multiplication  of  the  cells  if  the  process  is  too  ac- 
tive, and  howr  it  would  tend  to  promote  the  advance  of 
disease  in  organs  in  which  rapid  change  in  the  cells  char- 
acterizes the  normal  state."* 

Non-living  pus-corpuscles  are  round  and  granular,  about 
•g^Q-oth  of  an  inch  in  diameter.  Dilute  acetic  acid  renders 
them  transparent,  and  brings  into  view  one  or  more  nu- 
clei, bright  and  sharply  defined.  Neutral  alkaline  salts 
shrivel  the  pus-globules  and  caustic  alkalies  destroy  them- 
Besides  the  globules,  pus  often  contains  free  nuclei,  red 
blood-corpuscles,  epithelium,  remains  of  connective  tissue, 
crystals  of  the  triple  phosphates,  infusoria,  etc.  The  in- 
spissation  of  pus  sometimes  results  in  a  cheesy  metamor- 
phosis or  cassation,  which  has  been  called  tuberculization  of 
pus  (see  the  section  on  Fatty  Degeneration,  page  233). 

In  addition  to  pus-cells,  there  is  in  inflammation  always 
more  or  less  fluid  exudation,  or  inflammatory  effusion. 
This  differs  from  the  ordinary  liquor  sanguinis  of  the  ves- 
sels in  health  by  containing  a  larger  proportion  of  albu- 
men and  fibrinogenous  substance,  as  well  as  an  excess  of 
phosphates  and  carbonates.  This  exudation  may  be  in- 
terstitial when  between  the  tissues  and  parts,  parenchym- 
atous  if  seated  within  the  tissues  so  as  to  enlarge  them, 
or  free  if  on  free  surfaces  or  natural  cavities. 

Serous  exudations   on  free   surfaces  are  called  flux  or 

*  The  Physiological  Anatomy  and  Physiology  of  Man,  by  Todd, 
Bowman,  and  Beale.  Part  I. 


254  THE    MICROSCOPIST. 

serous  catarrh  ;  into  serous  cavities  inflammatory  dropsy  ; 
into  tissues,  inflammatory  oedema  ;  under  the  epidermis, 
serous  vesicles,  etc.  A  serous  exudation  containing  albu- 
men is  found  in  many  inflammations  of  the  kidneys  (al- 
buminuria),  and  of  the  intestine  (dysentery),  etc. 

Mucous  exudation,  or  mucous  catarrh,  occurs  oftenest 
on  mucous  membranes,  from  the  mingling  of  the  epithe- 
lial cells  with  the  increased  flow  from  the  vessels.  The 
term  "  catarrh  "  came  from  the  ancient  idea  that  in  a  cold 
liquid  flows  from  the  ventricles  of  the  brain  through  the 
ethmoid  bone  and  nose. 

In  catarrhal  inflammation  of  the  mucous  membrane 
there  is  first  hypersemia,  then  swelling  of  the  membrane 
and  lymph-follicles  with  an  increased  production  of  epi- 
thelial and  mucous  elements.  The  excessive  growth  of 
bioplasm  in  these  elements,  according  to  Beale,  changes  a 
simple  mucous  catarrh  into  a  purulent  one  (Fig.  203). 


FIG.  203. 


Catarrh  (purulent)  of  conjunctiva,     a.  Epithelium.     6.  Connective  tissue    stratum  of 
the  mucosa.— After  EINDFLEISCH. 

In  catarrhal  (lobular  or  broncho)  pneumonia  there  is  a 
proliferation  of  the  alveolar  epithelium  of  lobules  or 
groups  of  lobules  connected  with  those  bronchial  tubes  in 
which  the  catarrhal  changes  first  began  (Fig.  204). 

If  the  patient  recover,  but  the  retained  substances  are 
incompletely  removed,  a  thickening  of  the  walls  may  re- 
sult, with  the  formation  of  a  caseous  nodule. 


THE    MICROSCOPE    IN    PATHOLOGY. 


255 


Desquamative  catarrh  of  the  kidneys,  Fig.  205,  hegins 
with  a  granular  cloudiness  and  falling  off  of  the  epithe- 


FlG.  204. 


Catarrhal  pneumonia.  One  and  a  half  of  an  alveolus.  The  tortuous  capillaries  of 
the  septa  injected.  Filling  of  the  lumina  with  epithelial  cells  of  the  walls  which 
multiply  by  division.  1-300.— After  BJNDFLEISCH. 

lial  lining  of  the  uriniferous  tubules,  and  an  active  prolif- 
eration of  the  cells. 

FIG. 205. 


Transveise    and  oblique  sections  of  catarrhal  urinary  tubuli.     1-500.  —  After    EIND- 

FLEISCH. 

Rindfleisch  calls  vesicles  and  pustules  produced  by  in- 
flammation of  the  skin,  an  acute  purulent  catarrh  of  the 
skin,  in  which  a  primary  serous  catarrh  (vesicle)  became 
a  purulent  one  (pustule).  Eczema  he  terms  a  chronic 


256 


THE    MICROSCOPIST. 


catarrh  of  the  skin,  having  its  origin  in  hypersemia  of  the 
papillary  layer  (Fig.  206). 


FIG.  206, 


^_  A 


Vertical  section  through  the  skin  after  chronic  eczema,  a.  Horny  layer,  b.  Mucous 
layer  of  epidermis,  c.  Pigmented  stratum  of  cylindrical  cells,  d.  Papillary  layer,  e. 
Cutis  pervaded  by  stripes  of  pigment. — After  EINDFLEISCEI. 

The  stratum  of  Malpighi  in  the  skin  is  analogous  to 
the  softer  epithelium  of  mucous  surfaces,  but  catarrhal 
processes  in  the  skin  are  modified  by  the  horny  layer, 
which  is  first  destroyed  in  the  instances  referred  to,  and 
then  the  multiplying  epithelium  cast  off. 

Fibrinous  exudation  consists  of  fluid  from  the  hyperse- 
mic  vessels,  which  coagulates  into  fibres  between  whose 
meshes  serum  is  confined.  Pus-corpuscles  are  generally 
mixed  with  the  exudation,  constituting  a  fibrino-purulent 
exudation.  These  occur  principally  on  the  surface  of  serous 
membranes.  The  coagulated  fibrin  either  glues  the  two 
surfaces  of  the  membrane  together,  or  forms  a  slightly 
adherent  layer  of  membrane,  in  which  the  exuded  cells 
develop  a  true  connective  tissue  (Fig.  207). 

The  false  membranes  which  occur  in  pleuritis  or  peri- 
carditis, generally  of  rheumatic  origin,  are  examples  of 


THE    MICROSCOPE    IN    PATHOLOGY. 


257 


this  result.     The  formation  of  pus  in  serous  cavities  (em 
physema,  etc.)  is  well  illustrated  in  Fig.  208. 


FIG.  207. 


,„,•,.••" 

Adhesive  inflammation.  Diaphragmatic  pleura,  a.  Contiguous  muscular  structure  of 
diaphragm,  b.  Subserosa.  c.  Serosa.  d.  Boundary  of  the  serosa  and  the  exudation,  e. 
Exudation.  1-400.— After  RINDFLEISCH. 

Croupous  exudation  differs  from  fibrinous  by  having  its 
origin  in  a  peculiar  metamorphosis  of  epithelium  (Fig. 

FIG.  208. 


Purulent  inflammation  upon  the  serosa  of  the  uterus,  a.  Serosa  infiltrated  with  color- 
less blood-corpuscles.  6.  Surface  secreting  pus-corpuscles,  c.  Muscular  structure.  1-500. 
—After  RINDFLEISCH. 

209).     Wagner  has  shown  that  this  change  in  the  cells  re- 

17 


258 


THE    MICROSCOPIST. 


suits  in  a  delicate  network,  forming  by  its  accumulation 
a  flat  grayish-white  croupous  membrane,  or  isolated  de- 
posits. According  to  this  view,  the  network  of  croup- 


FIG.  209. 


Fibrinous  degeneration  of  pavement  cells. — After  E.  WAGNER. 

membrane  occupies  the  place  of  epithelium.  Other  pathol- 
ogists  regard  the  network  as  analogous  to  the  fibrinous 
network  of  inflamed  serous  membranes.  Croup  of  the 


FIG.  210. 


Croup  of  the  trachea,  a.  The  undermost  layer  of  pseudo-membrane.  6.  The  base- 
ment membrane,  c.  The  subepithelial  germinal  tissue,  d.  Excretory  duct  of  a  mucous 
gland,  from  which  a  clear  mucus  is  evacuated  and  lifts  off  the  pseudo-membrane.  1-1000. 
— After  RINDFLEISCH. 

larynx  and  trachea  shows  a  combination  of  catarrh  and 
pseudo-membranous  exudation  (Fig.  210). 


THE    MICROSCOPE    IN    PATHOLOGY.  259 

Croupous  pneumonia  is  generally  an  independent  affec- 
tion, while  the  catarrhal  and  interstitial  forms  of  inflam- 
mation of  the  lungs  usually  result  from  preceding  bron- 
chial or  pulmonary  lesion.  The  first  stage  is  that  of 
engorgement,  in  which  the  capillaries  dilate  and  coil  so 
as  greatly  to  diminish  the  air  capacity  of  the  alveoli.  In 
the  second  stage,  that  of  red  hepatization  (Fig.  211),  the 

FIG.  211. 


Recent  croupous  pneumonia,    a.  Alveolar  septa  with  injected  capillary  vessels.    6.  The 
exudation.    1-300.— After  RINDFLEISCII. 


exuded  contents  of  the  capillaries  of  the  air-cells,  red  and 
white  corpuscles,  and  serum,  are  coagulated  by  the  fibrin 
into  a  solid  body.  The  third  stage  is  that  of  yellow  or 
gray  hepatization,  characterized  by  a  greater  proportion 
of  white  blood-cells  and  their  progeny,  mingled  with  the 
results  of  commencing  fatty  metamorphosis.  Purulent 
infiltration,  or  resolution,  is  sometimes  called  the  fourth 
stage  of  this  disease.  Here  the  fibrin  melts  down  to  a 
soft  amorphous  gelatin,  and  the  young  cells  undergo  fatty 
degeneration.  Granular  pigment  also  is  mixed  with  the 


260 


THE    MICROSCOPIST. 


softened  matters,  and  appears  in  the  expectoration  (Fig. 
212).  Instead  of  resolution,  in  which  the  exudation  is 
absorbed  or  cast  out  by  the  sputum,  abscess,  or  gangrene, 
or  chronic  pneumonia  may  result,  though  rarely. 

Diphtheritic  exudation  accompanies  a  greater  hyperremia 
of  the  mucous  surface  than  croupous  inflammation,  and 
even  of  the  submucous  tissue,  with  a  gangrenous  separa- 
tion of  the  infiltrated  parts.  Between  the  croupous  and 
diphtheritic  forms  of  exudation  there  is  every  possible 
transition. 


FIG.  212. 


Croupous  pneumonia  in  a  later  stage  of  development.    Melting  down  of  the  exudation. 
Catarrhal  desquamation  of  the  alveolar  walls.    1-300. — After  RINDFLEISCH. 

Buhl  regards  diphtheritis  as  a  general  disease,  which 
may  be  termed  acute  tissue  necrosis,  and  is  different  from 
inflammatory,  typhous,  scarlatinous,  or  other  forms  of 
tissue  necrosis. 

The  occurrence  of  fungi  in  diphtheritic  exudation  is 
almost  constant.  The  leptothrix  buccalis  is  the  most  com- 


THE    MICROSCOPE    IN    PATHOLOGY. 


261 


mon  form.  Similar  forms  occur  in  croup-membrane. 
Some  suppose  the  fungus  to  be  the  primary  cause  of  the 
disease,  but  the  decaying  morbid  matter  may  merely  form 
the  habitat  (see  page  136). 

RESOLUTION   AND    ORGANIZATION. 

If  the  injury  sustained  by  the  tissue  is  not  severe,  or 
by  medical  skill  the  vascular  activity  is  lessened,  the  in- 


Fic.  213. 


0   O 


f 


Section  through  the  border  of  a  healing  surface  of  granulation,  a.  Section  of  pus. 
b.  Tissue  of  granulation  (germinal  tissue)  with  capillary  loops,  whose  walls  consist  of  a 
longitudinal  layer  of  eel  Is,  decreasing  in  thickness  from  within  outwards,  c.  Beginning 
of  the  cicatricial  formation  in  the  deep  layers  (spindle-cell  tissue),  d.  Cicatricial  tissue. 
e.  Complete  epithelial  covering.  The  central  layer  of  cells  consists  of  serrated  cells. 
/.  Young  epithelial  cells,  g.  Zone  of  differentiation.  1-300.— After  RINDFLEISCH. 

flammation  may  gradually  subside  or  terminate  in  reso- 
lution.    The  congestion  diminishes,  the  emigration  ceases, 


262  THE    MICROSCOPIST. 

some  of  the  cells  undergo  fatty  degeneration  and  are  ab- 
sorbed, others  are  removed  by  the  lymphatics,  and  the 
tissue  returns  to  its  normal  condition. 

If  the  inflammation  does  not  end  in  resolution,  after  a 
diminution  of  intensity,  there  may  be  an  organization  of 
many  of  the  new  cells  into  a  form  of  fibrillated  tissue,  as 
in  the  healing  of  wounds  by  uthe  first  intention,"  and  in 
many  chronic  inflammations  of  the  liver,  kidney,  etc.  In 
this  cicatricial  tissue  the  cells  become  spindle-shaped  or 
elongated,  with  tapering  ends.  Sometimes,  according  to 
Green,  a  sort  of  adenoid  tissue  results,  consisting  of 
meshes  of  fibrillated  material  inclosing  lyrnphoid  cells. 

After  suppuration,  organization  takes  place  by  granu- 
lation or  the  "second  intention"  It  takes  place  wherever 
the  injured  tissue  presents  a  free  surface  to  the  air,  as  in 
an  ulcer,  or  in  a  wound  left  open,  etc.  (Fig.  213).  The 
young  cells  of  the  superficial  layer  develop  into  granula- 
tion tissue,  which  forms  little  papilliform  nodules  or  granu- 
lations. The  form  of  these  granulations  seems  determined 
by  the  new  capillary  bloodvessels  which  grow  rapidly  in 
the  new  tissue.  The  deeper  layers  of  the  tissue  gradually 
develop  into  fibrillated  tissue,  while  the  cells  on  the  sur- 
face of  the  granulations  and  transuded  liquid  from  the 
vessels  are  discharged  as  pus.  The  first  formation  of  epi- 
thelium seems  to  consist  of  pus-corpuscles  not  thrown  off, 
yet  the  influence  of  the  neighboring  normal  epithelium  is 
seen  in  the  proliferating  margins,  as  w^ell  as  in  the  effect 
of  skin-grafting,  as  it  is  called,  on  the  surface  of  an  ulcer. 
The  new  epithelium  alwa3Ts  remains  thin  and  dry. 

PATHOLOGICAL  NEW  FORMATIONS. 

Increased  nutrition  leads  not  only  to  the  enlargement 
of  the  component  elements  of  a  tissue,  but  also  to  the 
production  of  new  elements  by  proliferation  of  bioplasm 
constituting  new  formations.  These  may  be  either  in- 
flammatory or  non-inflammatory  growths,  occurring  as 


THE    MICROSCOPE    IN    PATHOLOGY.  263 

tumors,  infiltrations,  or  numerical  hypertrophies,  the  lat- 
ter differing  from  simple  hypertrophies,  or  increased  size 
of  the  elements  of  tissues,  by  increase  in  the  number  of 
the  elements,  as  of  the  muscular  fibres  in  hypertrophied 
muscle,  etc. 

New  formations  are  in  all  cases  the  direct  product  of 
pre-existing  cellular  elements,  and  their  development  re- 
sembles more  or  less  the  normal  tissues.  In  other  words, 
every  pathological  growth  has  its  physiological  prototype. 
If  it  is  similar  in  structure  and  development  to  the  tissue 
from  which  it  originates,  or  in  which  it  is  situated,  it  is 
called  homologous  ;  when  it  differs,  heterologous. 

The  elements  from  which  new  growths  most  frequently 
originate  are  those  of  the  common  connective  tissue  with  its 
bloodvessels  and  lymphatics.  This  tissue  must  be  distin- 
guished from  formed  connective  substances,  as  bone,  ten- 
don, cartilage,  etc.  Two  kinds  of  cells  are  found  in  this 
tissue, — the  connective  tissue  cells,  which  are  stable,  and 
the  mobile  cells,  which  are  probably  wandering  leucocytes. 

The  first  result  of  the  abnormal  activity  of  these  cells  is 
to  produce  a  new  tissue, — embryonic  or  indifferent  tissue, — 
composed  of  small  roundish  cells,  about  o-o'or tb  of  an  inch 
in  diameter.  This  tissue  afterwards  develops  into  tissue 
of  permanent  growth,  resembling  the  immature  connective 
tissue  of  the  embryo,  and  like  that  capable  of  becoming 
fibrous  tissue,  cartilage,  bone,  etc. 

Next  to  common  connective  tissue,  the  epithelia,  surface 
and  glandular,  are  the  elements  from  which  new  forma- 
tions most  frequently  originate,  and  such  growths  gener- 
ally resemble  epithelium. 

From  the  higher  animal  tissues,  muscle  and  nerve,  new 
growths  are  rare,  if,  indeed,  they  really  occur  at  all. 
Beale  says  "the  fully  formed  anatomical  elements  of  a 
normal  tissue  could  not  give  origin  to  a  morbid  growth." 

The  term  malignancy  is  applied  to  a  property  possessed 
by  many  tumors  of  recurring  after  removal,  of  infecting 


264  THE    MICROSCOPIST. 

neighboring  lymphatic  glands,  and  of  reproducing  them- 
selves in  distant  organs.  It  is  not  confined  to  carcinomas 
or  cancers,  since  many  sarcomas  are  just  as  malignant. 

Pathological  new  formations  are  subject  to  retrogressive 
changes  similar  to  those  of  physiological  tissues.  Deficient 
supply  of  blood  is  followed  by  fatty  degeneration,  with  its 
varied  terminations, — softening,  caseation,  and  calcifica- 
tion. Pigmentary,  colloid,  and  mucoid  degeneration  may 
also  occur,  or  inflammation.  In  addition,  one  form  of 
tissue  may  be  transformed  into  another,  especially  of  the 
same  group,  as  of  connective  tissue  elements.  Thus  can- 
cers may  form  in  cicatrices  and  tumors  of  various  kinds, 
sarcomas  in  fibromas,  etc. 

Pathological  new  formations  have  been  variously  classi- 
fied. For  convenience  of  the  student  we  divide  them  as 
follows: 

1.  Pathological  formation  of  cells 

2.  Pathological  growth  of  higher  animal  tissues. 

3.  Pathological  growths  of  connective  tissue  origin. 

4.  Pathological  growths  of  epithelial  origin. 

I.    NEW   FORMATION   OF    PATHOLOGICAL    CELLS. 

We  have  already  stated  that  proliferating  cells,  either 
tissue-cells  or  wandering  leucocytes,  produce  abnormally, 
first,  an  embryonic  or  indifferent  tissue.  This  seems  iden- 
tical with  granulation  tissue  (page  262).  From  it  various 
new  growths  proceed.  The  cells  multiply  as  in  normal 
tissues,  by  division,  budding,  or  endogenous  formation 
(page  125).  Cell  division  affects  the  entire  cell  nucleus, 
nucleolus,  and  bioplasm.  It  is  generally  accomplished 
quickly,  judging  from  experiments  on  the  warm  stage  of 
the  microscope  (page  42).  Budding  is  a  variety  of  self- 
division,  in  which  a  small  portion  of  bioplasm  is  protruded 
and  separated  so  as  to  become  an  independent  cell.  In 
exogenous  cell  formation  the  nucleus,  after  previous  di- 
vision of  the  nucleolus,  divides  into  two  or  more  nuclei. 


THE    MICROSCOPE    IN    PATHOLOGY. 


265 


In  the  giant  cells,  so  called,  the  nuclei  number  ten  to  fifty 
or  more.  Physiologically  these  occur  in  bone  marrow, 
where  they  are  regarded  as  transformed  osteoblasts,  and 
pathologically  in  granulation  tissue  and  many  tumors. 
In  soft,  yielding  tissues  their  form  is  roundish,  but  in 
fibrous  tissues  the  giant  cells  have  peripheral  processes 
(Fig.  214). 

FIG.  214. 


Giant  cells,     a.  Koundish  (Virchow).     b.  With   processes.     From  a  muscular  tumor 
(Billroth).— After  BJNDFLEISCH. 

Rindfleinch  has  pointed  out  a  cell-formation  in  nucleus- 
bearing  protoplasm,  where  apparently  free  nuclei  are  im- 
bedded in  homogeneous  substance,  but 
reagents  show  a  differentiation  of  the  FlG- 215- 

protoplasm,  so  that  to  each  nucleus 
belongs  a  small  round  cell.  This  is 
different  from  giant  cells,  and  occurs 
in  many  sarcomata  and  cancers  (Fig. 
215). 

Most  cells  are  capable  of  increase. 
The  movable  and  fixed  cells  of  con- 
nective tissue,  young  bone,  and  carti- 
lage cells  ;  the  youngest  layers  of  epi- 
thelial cells,  either  of  the  surface  or 
glandular;  the  nuclei  of  capillaries,  of  the  sarcolemma, 


Nucleated  protoplasm. 
Fragment  from  a  granula- 
tion. 


266  THE    MICROSCOPIST. 

etc.,  may  any  of  them  become  points  of  departure  for 
pathological  new  formations.  The  youngest  formed,  or 
embryonic  cells,  may  be  developed  like  the  tissues  of  the 
embryo,  may  become  connective  tissue  cells,  bone-corpus- 
cles, muscle-fibres,  and,  according  to  some,  true  epithe- 
lium, etc.,  or  cancer-cells,  sarcoma-cells,  etc.  The  cells, 
however,  which  rise  from  various  tissues  usually  give 
origin  to  definite  new  formations.  Thus  epithelial  forma- 
tions arise  from  epithelial  tissue ;  connective  tissue  forms 
from  connective  tissue,  etc. 

II.    PATHOLOGICAL   GROWTHS   OF   HIGHER,    ANIMAL    TISSUES. 

1.  Muscular  Tissue. — a.  Striated.     Virchow,  and  after 
him  Billroth  and  others,  have  shown  that  the  elements 
of  the  more  highly  organized  tissues,  as  the  nervous  and 
muscular,  are  rarely  imitated  pathologically. 

Systematic  writers  term  striated  muscular  tumors  rhab- 
domyoma,  or  true  myoma.  The  few  instances  referred  to 
consist  of  a  few  fibres  mixed  with  other  tissues  in  cystic 
tumors  of  the  ovary,  testicle,  etc. 

b.  Smooth  muscular-fibre  tumors,  or  leiomyoma, — fibroid, 
in  the  narrower  sense, — occurring  most  frequently  in  the 
body  of  the  uterus,  either  as  submucous,  intramural,  or 
subperitoneal  tumors,  are  so  similar  in  their  elements  to 
the  ordinary  fibroma  as  not  to  be  distinguished  from  it. 

2.  Nervous  Tissue. — The  term  neuroma  is  applied  to  a 
fibrous  tumor  on  a  nerve.     It  is  quite  doubtful  if  the  term 
is  applicable.     The  cases  recorded  are  small,  roundish, 
hard  tumors,  occurring  in  the  course  of  nerves,  and  nod- 
ules on  nerves  at  the  end  of  amputation  stumps.     They 
consist,  however,  of  increased  vascular  connective  tissue 
separating  the  nerve-fibres.     Rindfleisch  refers  to  a  case 
which  he  deems  a  true  neuroma.     He  says  it  is  the  first 
example  of  a  genuine  one,  yet  states  that  it  may  be  a 
hypertrophied  ganglion  of  the  sympathetic. 


THE    MICROSCOPE    IN    PATHOLOGY. 


267 


III.    PATHOLOGICAL    GROWTHS    OF   CONNECTIVE   TISSUE 
ORIGIN. 

a.  Common  Connective  Tissue  Type. 

1.  Fibroma  is  a  generally  innocent  growth,  consisting 
essentially  of  fibrous  tissue  (Fig.  216).     Fibromata  are 

FIG.  216. 


Transverse  section  of  a  fibroma  of  uterus.    1-300.    a.  Isolated  cellular  elements,    b.  An 
unravelled  fasciculus  of  the  fibroma.    1-500.— After  RINDFLEISCH. 

usually  circumscribed,  rarely  diffused,  and  are  composed 
of  interlaced  fibres  and  cells,  like  cicatricial  tissue.  The 
common  fibroid  is  so  dense  that  in  cutting  it  creaks  under 
the  knife. 

Fibromata  occur  on  the  trunk  and  extremities,  proceed- 
ing .from  the  skin  (as  elephantiasis  tuberosa,  etc.),  from  the 
subcutaneous  and  intermuscular  connective  tissue,  from 
fascia,  periosteum,  bones,  and  bone-marrow ;  in  the  uterus 
and  its  vicinity,  in  subserous  tissue,  in  submucous  tissue, 
especially  of  the  nose  and  throat ;  in  nerves  (as  common 
neuroma  and  the  subcutaneous  painful  tumor,  or  irritable 
tumor,  as  it  is  called) ;  in  glandular  organs,  as  the  mammae 
and  kidneys,  etc.  For  the  most  part  fibromata  grow  very 
slowly,  but  they  are  often  combined  with  other  forms. 


268 


THE    MICROSCOPIST. 


2.  Areola  fibroma,  or  fibro-cellular  tumor,  consists  of 
bundles  of  connective  fibres  with  spaces  containing  serous 
or  mucous  fluid.  It  occurs  in  circumscribed  or  diffuse 
form.  The  circumscribed  is  found  in  the  skin  and  sub- 
cutaneous tissue,  especially  of  the  scrotum,  labia  majora, 
around  the  vagina,  in  internmscular  connective  tissue, 
periosteum,  uterus,  mammae,  etc.  The  diffuse  occur  of ten- 
est  in  the  skin  as  soft  warts  (fibroma  molluscum,  Fig.  217); 

FIG.  217. 


Fibroma  inolluscum.  J.  Completed  tissue,  after  Virchow.  2.  Immature  condition. 
Formation  of  clefts  in  the  parenchymatous  islands.  1-200.  At  a,  the  lumen  of  a  vessel. 
—After  RINDFLEISCH.  • 

as  elephantiasis  of  the  scrotum,  prepuce,  labia,  clitoris,  of 
the  extremities,  nose,  etc. ;  and  as  polypi  in  the  submu- 
cous  tissue  of  the  pharynx,  nose,  uterus,  etc. 

.  •  , ;.   b.  Mucous  Tissue  Type. 

1.  Myxoma,  or  mucous  tumor,  occurs  either  pure  or 
mixed  with  other  tissues.  It  consists  of  a  mucous  basis- 
substance,  with  stellate  or  spindle-shaped  anastomosing 
cells  (Fig.  218),  or  in  young  myxomas,  of  small  round 
cells,  like  mucous  corpuscles.  Myxoma  form  rapidly- 
growing,  soft,  knotty  swellings,  which  may  be  mistaken 
for  soft  cancers.  They  may  be  classed  with  benign  tu- 
mors, and  do  not  return  after  thorough  extirpation. 


THE    MICROSCOPE    IN    PATHOLOGY.  269 

Myxomata  occur  in  subcutaneous  and  intermuscular 
connective  tissue,  in  fasciae,  medulla  of  bones,  and  in  the 
interior  and  vicinity  of  glands.  A  myxoma  of  the  pla- 
centa has  been  described  as  a  vesicular  mole,  consisting 
in  a  hypertrophy  of  the  mucous  tissue  of  the  tufts  of  the 
chorion,  producing  tumors,  varying  to  the  size  of  a  cherry 

FIG.  218. 


Hyaline  inyxoma  of  the  subcutaneous  connective  tissue  in  the  neighborhood  of  the 
angle  of  the  jaw.    1-300.— After  RINDFLKISCH. 

or  larger ;  the  whole  mass  may  attain  the  size  of  a  man's 
head.  The  fetal  development  in  such  a  case  varies  ac- 
cording to  the  mass  of  the  tumors. 

c.  Vascular  Connective  Tissue  Forms. 

1.  Angioma,  or  vascular  tumor,  is  composed  of  blood- 
vessels held  together  by  a  small  amount  of  connective 
tissue.  The  angiomata  include  the  various  forms  of  nsevi, 
the  erectile  tumors,  and  aneurism  by  anastomosis. 

(1.)  Capillary  angioma,  nsevus  vasculosus,  or  teleangiec- 
tasia,  is  generally  congenital.  It  occurs  oftenest  on  the 
skin,  in  the  papillary  layer  (mole,  mother's  mark,  etc.), 
although  it  may  occur  in  other  structures.  It  may  vary 
in  size  from  that  of  a  millet-seed  to  the  occupancy  of  the 
entire  face  or  extremity.  It  is  flat,  lobed,  generally  bluish 
or  dark  red,  arid  consists  of  tortuous,  varicose,  or  aneuris- 
mal  capillary  vessels  and  wavy  connective  tissue. 


270 


THE    MICROSCOPIST. 


(2.)  Cavernous  or  venous  angioma,  erectile  tumor,  or 
aneurism  by  anastomosis,  is  generally  round,  from  the 
size  of  a  bean  to  that  of  a  walnut.  It  is  similar  in  struc- 
ture to  the  erectile  cavernous  tissue  of  the  penis  and  clit- 


FIG.  219. 


The  substance  of  the  cavernous  tumor  in  full  development.    1-300.    From  a  cavernous 
tumor  of  orbit.— After  RINDFLEISCH. 

oris,  consisting  of  a  network  of  fibres  containing  blood 
(Fig.  219).  They  are  generally  of  a  bluish  color.  Venous 
angiomata,  consisting  mainly  of  enlarged  and  tortuous 
veins,  are  often  seen  as  internal  or  external  heernorrhoidal 
tumors. 

(3.)  Arterial  angioma  is  sometimes  met  with,  especially 
in  the  branches  of  the  temporal  and  occipital  arteries. 

(4.)  Lymphatic  angioma  is  a  similar  dilatation  of  the 
lymphatic  vessels,  and  has  been  principally  noticed  in 
connection  with  elephantiasis.  Lymphangiomata  of  the 
kidneys  and  of  the  skin  have  also  been  described. 

2.  Thrombosis  is  a  coagulation  of  the  blood  in  the  ves- 
sels during  life,  from  impeded  blood-flow  or  changes  (as 
inequalities)  in  the,  walls  of  the  vessels.  It  depends  on 
separation  of  the  fibrin  from  the  blood.  Dr.  Schmidt  has 
shown  that  the  blood-corpuscles  contain  an  albuminoid 


THE    MICROSCOPE    IN    PATHOLOGY. 


271 


substance  (globulin,  fibrino-plastic  substance),  which  en- 
ters into  union  with  a  similar  (fibrinogenous)  substance, 
so  as  to  form  fibrin,  the  molecules  of  which  have  a  great 
attraction  for  each  other,  producing  a  characteristic  mi- 
croscopic network  of  round  filaments. 

Thrombi  must  not  be  confounded  with  the  coagula 
found  in  the  dead.  If  the  death-struggle  has  been  long 
coagula  are  generally  found  in  the  right  side  of  the  heart, 
often  extending  into  the  pulmonary  artery.  A  thrombus 
is  lighter,  firmer,  and  drier  than  a  coagulum,  and  is  often 
made  up  of  concentric  layers. 


Cross-section  through  a  thrombus  by  ligation  of  the  crural  artery,  thirty-seven  days 
old ;  hardened  in  alcohol,  treated  with  dilute  acetic  acid,  and  then  with  a  little  ammonia- 
a.  Capillaries,  b.  The  cell-net  of  the  colorless  blood-corpuscles.  In  the  basis-substance 
the  contours  of  the  red  blood-corpuscles. — After  RINDFLEISCH. 

A  thrombus  once  formed  either  organizes  or  softens. 

If  it  organizes,  the  thrombus  is  gradually  changed  into 
connective  tissue.  This  is  by  virtue  of  the  vital  power 
of  the  bioplasts,  or  white  corpuscles.  Thrombi  have  been 
produced  in  animals  by  ligation,  and  cinnabar  injections 
into  the  blood  have  shown  the  wrandering  leucocytes, 
carrying  cinnabar,  at  work  in  the  blood-clot.  They  send 
out  processes  in  various  directions,  which  touch  each 
other  and  form  a  more  delicate  net  with  nuclei  at  the 
points  of  intersection  (Fig.  220). 


272 


THE    MICROSCOPIST. 


SOOD  after  vessels  are  formed  in  the  thrombus,  which 
give  it  an  organlike  connection  with  the  body,  as  other 
pathological  new  formations.  These  vessels  may  widen 
and  become  cavernous,  as  in  Fig.  221,  and  as  the  walls 
become  thinner  and  finally  disappear  the  thrombus  ceases 
to  exist. 


FIG.  221. 


a 


From  the  cross-section  of  an  arterial  thrombus  of  three  months,  a.  Media,  only  the 
innermost  layers.  6.  Boundary  lamella  of  the  media  and  intiuia.  c.  Intinia.  d.  Bound- 
ary of  intiiaa  towards  the  thrombus,  e.  Thrombus,  /.  Lurnina  of  vessels.  Distinct 
epithelium.  1-300.— After  RINDFLFISCH. 

The  softening  of  the  thrombi  is  a  dangerous  process. 
Fragments  may  be  carried  from  the  radicles  of  the  vena 
cava  through  the  right  heart  to  the  lungs  ;  from  the  radi- 
cles of  the  pulmonary  veins  through  the  left  heart  to  the 
various  organs  of  the  body  ;  or  from  the  radicles  of  the 
portal  vein  to  the  liver.  Such  particles  may  occlude  the 
vessel  in  which  they  are  found,  producing  embolism,,  the 
results  of  which  may  depend  on  the  mechanical  obstruc- 
tion to  the  circulation  (anaemia  and  softening),  or  on 
the  irritating  or  infective  properties  of  the  emboli  (pyae- 
mia). 

a.  Adenoid  or  Eeticular  Connective  Type. 

1.  Lymphoma. — This  is  a  new  formation  of  lymphatic 
or  adenoid  tissue,  and  is  generally  found  as  small  tumors 
or  infiltrations,  consisting  of  rounded  bright  nuclei,  and 


THE    MICROSCOPE    IN    PATHOLOGY. 


273 


small  cells,  like  leucocytes,  lying  in  semifluid  or  fibrous 
intermediate  substance.  Lymphomata  occur  in  typhoid 
fever  in  the  small  intestine,  in  the  mesenteric  glands,  and 
liver.  Lymphatic  tissue  always  consists  of  a  reticulum  of 
branched  cells,  within  the  meshes  of  which  the  lymphatic 
corpuscles  are  contained.  It  is  closely  allied  to  embry- 
onic tissue,  and  is  easily  influenced  by  any  irritation 
whatever  to  excessive  development.  Inflammatory  states 

FIG. 222, 


From  the  section  of  the  cervical  gland  of  a  dog,  swollen  to  the  size  of  a  hazolnut  after 
artificially  produced  inflammation  of  the  lips.  1-500.  After  Billroth.  Connective  tissue 
septum.  Sinus  termiualis.  Border  of  lymph  alveoli.— After  RINDFLEISCH. 

of  the  organs  from  which  the  glands  receive  their  lymph 
produce  suppurative,  cheesy,  and  indurated  lymphade- 
nitis (Fig.  222). 

18 


274  THE    MICROSCOPIST. 

The  adenomata  are  generally  innocent.  The  glands 
which  are  most  prone  to  increased  growth  are  the  cervical, 
submaxillary,  axillary,  inguinal,  and  abdominal  glands. 
Sometimes  several  glands  unite  so  as  to  form  large  lobu- 
lated  tumors.  The  enlargement  of  the  spleen  in  ague  is 
probably  of  this  nature.  Leucocythgemic  new  formations 
occur  generally  in  the  spleen,  the  lymph  glands,  and  per- 
haps the  medulla  of  bones. 

2.  Tubercle  is  an  infiltrated  or  nodular  new  formation, 
generally  multiple,  or  miliary,  non-vascular,  round  or  ir- 
regular, made  up  of  large  and  small  nuclei,  indifferent 
cells,  and  giant  cells,  imbedded  in  reticular  tissue.  After 
long  induration  it  passes  into  cheesy  atrophy,  or  into  soft- 
ening, and  produces  not  only  local  affections  but  also  con- 
stitutional disease  (tuberculosis  and  scrofulosis).  It  was 
formerly  considered  to  be  a  specific  non-inflammatory 
growth  originating  spontaneously,  and  characterized  by  a 
regular  succession  of  changes,  first  gray  and  translucent, 
then  opaque,  and  finally  caseous.  Modern  histologists  re- 
gard it  as  due  to  infection  from  the  absorption  of  the 
products  of  inflammatory  processes.  Caseation  after  fatty 
degeneration  (page  233)  may  become  a  focus  of  self-infec- 
tion, so  that  caseation  and  tuhercle  may  occur  side  by 
side.  The  nodules  of  tubercle  are  sometimes  microscopic 
in  size,  as  in  the  liver  or  meninges  of  the  brain.  When 
they  reach  the  size  of  a  millet-seed  they  are  termed  mili- 
ary tubercles  (gray  tubercle,  semi-translucent  granulation). 
If  as  large  as  a  pea,  cherry,  egg,  etc.,  they  are  large,  tuber- 
cles or  conglomerate  nodules.  Still  later  they  are  known 
as  yellow  tubercles,  from  their  being  yellow  and  cheesy  in 
the  centre. 

In  Fig.  223  is  a  view  of  two  broncho-pneumonic  depots, 
the  size  of  a  millet-seed,  illustrating  a  pseudo-tuberculous 
condition. 

See  also  page  254,  where  catarrhal  pneumonia  is  stated 
to  precede  a  caseous  nodule. 


THE    MICROSCOPE    IN    PATHOLOGY. 


275 


In  contrast  with  this  Fig.  224  shows  the  deposit  of 
miliary  tubercle  as  it  occurs   in   tubercular  meningitis. 


FIG.  223. 


Two  smallest  broncho-pneumonic  depots.  Tubercle  granulation  of  Laennec.  a,  a. 
The  luminaof  two  adjacent  small  bronchi,  the  caseous  secretion  partially  fallen  out; 
the  walls  infiltrated  with  cells  and  directly  going  over  into  catarrhal  infiltration  of  the 
surrounding  parenchyma.  By  the  course  of  the  elastic  fibres  we  may  recognize  every- 
where how  large  the  number  of  infiltrated  alveoli  is.  6,  6,  b.  Bloodvessels.  1-100  mm. — 
After  EINDFLEISCH. 

The  inflammatory  growth  originates  in  the  perivascular 
lymphatic  sheaths  which  inclose  the  small  arteries  of  the 


276 


THE    MICROSCOPIST. 


pia  mater.     The  cells  of  the  sheath  multiply,  and  numer- 
ous gray  nodules  are  produced  around  the  vessel. 

Microscopically,  Wagner  describes  fresh  miliary  tuber- 
cle as  consisting  of  one  or  more  (from  four  to  six  gener- 
ally) rounded  follicles  or  nodules,  each  composed  of  a 


Vertical  section  through  the  pia  mater  and  the  contiguous  portion  of  the  cortex  of 
brain  in  tubercular  meningitis,  a,  a.  A  larger  vessel  of  the  pia  mater  whose  entire 
sheath  is  intiaiumatorily  infiltrated.  6,6.  Lymph-spaces  of  the  pia  mater  with  com- 
mencing tubercular  proliferation  of  the  endothelia.  c.  Miliary  tubercle  of  the  pia  mater. 
d.  Outermost  layer  of  cortex  of  brain  infiltrated  with  round  cells,  e.  Normal  brain-sub- 
stance. /,/.  Proper  cerebral  vessels  in  a  state  of  tuberculous  degeneration. — After  RIND- 

FLEISCH. 

reticulum  and  cellular  elements.  The  latter  are  free  nu- 
clei, cells  like  leucocytes  with  one  or  two  nuclei,  and  in 
the  centre  of  the  follicle  one  or  more  polynuclear  giant 
cells.  The  latter  are  granular  and  branching,  with  20  to 
100  rounded  and  comparatively  large  nuclei.  In  addition 
there  are  cells  of  intermediate  size,  epithelial-like,  rounded, 
and  finely  granular.  Tubercle  always  occupies  the  place 
of  normal  tissue,  which  is  either  wasted  or  pushed  aside 
by  it. 

There  may  be  atrophy  or  necrosis  of  the  elements  of 
tubercle,  after  which  cornification  may  transform  it  into 
a  hard  horny  mass.  Eesorption  rarely  occurs,  but  calci- 


THE    MICROSCOPE    IN    PATHOLOGY.  277 

fication  will  sometimes  produce  stony  masses,  which  are 
occasionally  laminated.  Most  often  softening  or  liquefac- 
tion occurs  simultaneously  with  cheesy  metamorphosis, 
leading  on  mucous  surfaces  to  tuberculous  ulcers,  and  in 
the  parenchyma  of  organs  to  tuberculous  cavities  or  ab- 
scesses. 

e.  Neuroglia  or  Nerve-cement  Type. 

1.  Glioma  is  an  increase  of  the  elements  of  the  finely 
granular  and  reticular  tissue  or  connective  substance  of 
nerve.  The  nervous  elements  do  not  participate  in  it. 
Glioma  formerly  went  under  the  name  of  sarcoma,  being 
considered  a  variety  of  round-celled  sarcoma,  but  the  lo- 
cality and  origin  of  these  tumors  entitle  them  to  separate 
consideration.  They  are  generally  cerebral,  and  produce 
symptoms  of  pressure  or  irritation.  In  the  retina  they 
may  begin  as  a  white  nodule,  which  grows  until  it  may 
project  from  the  orbit  as  a  large  fungous  tumor.  Accord- 
ing to  the  relative  proportion  of  cells,  intermediate  sub- 
stance, and  vessels,  they  are  divided  into  soft,  hard,  and 
teleangiectatic  gliomas.  Gliomas  are  of  very  slow  growth, 
and  may  become  metamorphosed  by  haemorrhages,  fatty 
degeneration,  and  cystoid  softening.  Healing  may  be 
possible  through  fatty  metamorphosis. 

/.   Type  of  Fatty  Tissue. 

1.  Lipoma. — A  general  formation  of  new  adipose  tissue, 
hereditary  or  acquired,  is  termed  obesity.  A  local  and  cir- 
cumscribed formation  is  a  lipoma  or  fatty  tumor.  The 
connective  tissue  unites  the  fat-cells  in  masses  and  lobules, 
and  forms  a  distinct  capsule.  Lipomata  are  sometimes 
pedunculated.  Their  growth  is  slow,  and  although  they 
may  attain  considerable  size  they  are  perfectly  benign 
tumors. 

Xanthoma,  or  xanthelasma,  are  small  yellowish  fatty 
tumors  of  the  skin,  generally  of  the  face  or  eyelids.  They 


278  THE    MICROSCOPIST. 

are  sometimes  nodular,  like  millet-seeds  or  grains  of  wheat, 
isolated  or  in  groups. 

g.   Cartilage  Type. 

1.  Enchondroma  or  Cartilaginous  Tumor. — Like  carti- 
lage, this  consists  of  cells  and  intercellular  substance,  the 
latter  being  hyaline,  fibrous,  or  mucoid.  The  cells  are 
often  spindle-shaped  or  stellate.  Enchondromata  rarely 
develop  from  cartilage,  but  from  bone  and  connective  tis- 
sue. A  large  majority  have  their  seat  upon  bones,  espe- 
cially at  the  diaphyses  of  the  long  bones.  They  are  usu- 
ally single,  except  on  the  fingers  and  toes,  where  they  are 
often  multiple.  An  ossifying  enchondronia  is  called  osteo- 
chondroma.  The  enchondromata,  especially  those  which 
originate  from  cartilage,  may  be  regarded  as  benign,  yet 
encapsulated  forms  originating  from  bone  or  connective 
tissue  are  often  injurious  from  the  rapidity  of  their  growth. 
The  softer  forms,  such  as  occur  in  the  medulla  of  bone, 
are  sometimes  malignant. 

h.   Type  of  Bone  Formation. 

1.  Osteoma. — An  osseous  or  bony  tumor.  An  outgrowth 
from  pre-existing  bone  is  an  exostosis  or  osteophyte.  Such 
outgrowths  proceed  from  the  periosteum,  the  articular 
cartilage,  or  the  medulla.  In  the  latter  case  they  might 
be  properly  termed  enostoses.  These  are  homologous  tu- 
mors, since  they  are  similar  in  structure  to  the  tissue  in 
which  they  are  found.  The  osteomata,  however,  may  be 
heterologous,  as  growing  from  connective  tissue  or  carti- 
lage apart  from  bone.  They  are  of  two  kinds :  1.  The 
ivory  or  hard  tumors,  in  which  there  is  a  marked  absence 
of  cancellated  bony  tissue.  2.  The  soft  or  cancellous, 
which  are  spongy.  The  medullary  cavities  are  sometimes 
quite  large. 

Osteomata  are  innocent  tumors.    Those  osseous  growths 


THE    MICROSCOPE    IN    PATHOLOGY. 


279 


which  exhibit  malignancy  are  ossified  sarcomata  or  ossi- 
fied cancers. 

i.  Other  Forms  Analogous  to  Connective  Tissue  Type. 

1.  Sarcoma. — Fibro-plastic  or  fibro-cellular  tumor.  It- 
belongs  to  the  group  of  connective  substance  tumors  by 
some  of  its  affinities,  but  is  to  be  distinguished  by  the 
greater  development  of  its  cellular  elements.  All  the 
sarcomata  consist  of  embryonic  connective  tissue,  and  the 

FlG.  225. 


Round-celled  sarcoma,  a.  Vascular  lumina.  6.  Parenchyma  partly  brushed  out,  so 
that  the  hardened  basis-substauce  appears  as  an  elegant  network.  1-300.— After  RIND- 
FLEISCH. 

several  varieties  are  dependent  on  the  size  and  shape  of 
the  cells  and  the  nature  of  the  intermediate  substance. 
They  include  what  are  termed  recurrent,  fibroid ,  and  mye- 
loid  tumors. 

(1.)  Round-celled  sarcoma  is  allied  to  granulation  and 
embryonic  tissues  (page  262). 

a.  The  granulation-like  round-celled  sarcoma,  of  soft  con- 
sistence, containing  embryonic  cells  in  a  homogeneous  or 
finely  granular  intercellular  substance. 


280 


THE    MICROSCOPIST. 


b.  The  lymphatic  glandlike  round-celled  sarcoma  exhibits 
round  cells  in  a  delicate  network  of  fibres  among  wide 
thin-walled  capillaries  (Fig.  225). 

There  are  several  varieties  of  these  lymphadenoid  sar- 
comas, as  the  lipomatous  sarcoma,  in  which  the  cells  by 
infiltration  are  transformed  into  fat;  the  mucoid  sarcoma, 
from  mucoid  metamorphosis ;  and  the  large-celled  round- 
celled  sarcoma,  which  seems  almost  epithelial  in  its  char- 
acter of  cells,  with  a  large-meshed  network.  This  tumor 
is  soft  and  brainlike,  and  may  be  easily  confounded  writh 
the  following: 

c.  The  Alveolar  Round-celled  Sarcoma. — This  has  a  great 
resemblance  to  cancer,  and  has  been  called  sarcoma  carci- 
nomatodes.     It  consists  of  groups  of  cells  not  connected 


FIG   226. 


Alveolar  round-celled  sarcoma,  pigraented.  b.  Alveolus  from  which  the  ball  of  round 
cells  has  fallen  out.  c.  Vessel  with  pigmented  eridothelia.  d.  Piginented  round  cells. 
e.  Spindle  cells  forming  a  stroma.— After  RINDFLEISCH. 

by  basis-substance,  but  held  in  alveoli  or  clefts  of  connec- 
tive tissue.  The  cells  resemble  epithelium.  An  exceed- 
ingly malignant  variety  has  been  called  pigmentary  cancer 
(Fig.  226). 

(2.)  Spindle-celled  sarcomata  are  divided  into — a,  small- 
celled  spindle^elled  sarcomata  (Fig.  227),  which  resembles 


THE    MICROSCOPE    IN    PATHOLOGY.  281 

the  spindle-celled  tissue  of  recent  cicatrices  ;  b,  large-celled 
spindle-celled  sarcomata,  in  which  the  cells  attain  an  ex- 
cessive development  (Fig.  2i!8);  and  c,  the  pigmentary  sar- 
comata. 

FIG.  227. 


Spindle-celled  scarcoma.    Gaping  vascular  lamina.    The  cell  lines  are  divided  partly 
longitudinally,  partly  transversely.    1-300. — After  RINDFLEISCH. 


(3.)  The  giant-celled  sarcomata,  called  also  myelo-plastic 
and  myeloid  sarcomas,  contain  large  cells,  with  numerous 
nuclei  and  nucleoli  in  a  finely  granular  substance  (Fig. 
229).  These  occur  usually  on  bones. 

Sarcomata  are  rarely  found  in  internal  organs.  They 
usually  arise  from  common  connective  tissue,  and  the 
influence  of  locality  on  them  is  obvious.  Thus  on  the 
surface  of  bone  we  have  osteoid  sarcomata,  pigmented 
sarcomas  in  the  skin  and  choroid,  soft  and  gelatinous 
sarcomata  in  the  glands,  etc.  Complete  cure  sometimes 
follows  extirpation,  but  at  other  times  there  is  a  recur- 
rence in  the  cicatrix,  giving  rise  to  the  term  recurring 
fibroid.  Like  other  tumors  they  may  inflame  or  become 
atrophied,  or  fatty  metamorphosis,  calcification,  etc.,  may 
occur  in  them. 

2.  Syphiloma. — Gumma-syphiliticum.     Gummy  tumor. 


282 


THE    MICROSCOPIST. 


This  is  a  new  formation,  depending  on  constitutional 
syphilis.  Its  essential  elements  resemble  leucocytes  im- 
bedded in  connective  tissue  which  is  poor  in  vessels. 
It  exhibits  many  transitional  forms  to  granulation  tissue 


FIG.  228. 


Large-celled  spindle-celled  sarcoma. — After  VIRCHOW. 


and  sarcomata.  Atrophy  or  fatty  metamorphosis  of  the 
cells  may  produce  cavities  or  caverns  and  cicatricial  marks 
on  the  surface,  leading  to  deformities  (Fig,  230). 


THE    MICROSCOPE    IN    PATHOLOGY. 


283 


3.  Lupus  consists  of  nuclei  and  cells,  forming  a  diffuse 
or  nodular  infiltration  of  the  corium  of  the  skin,  generally 


FIG.  229. 


Giant  cells,     a.  Roundish  (Virchow).     6.  With  processes.     From  a  muscular  tumor 
(Billroth).— After  RINDFLEISCH. 

of  the  face,  and  sometimes  of  the  bordering  mucous  mem- 

FlG.  230. 


Syphilis  ot  liver,  a.  Left.  b.  Right  lobe  of  liver,  cc.  Connective  tissue  sheath,  which 
penetrates  the  organ  in  the  direction  from  the  porta  to  the  lig.  suspensorium,  and  con- 
tains gummata.  2-1.— After  RINDFLEISCH. 

brane.     Rindfleisch  considers  it  to  begin  with  a  luxuriant 


284  THE    MICROSCOPIST. 

cell  proliferation  in  the  interstitial  and  encapsuling  con 
nective  tissue  of  the  sebaceous  and  sweat  glands  (Fig. 
231).  If  the  skin  appears  normal,  or  there  is  a  moderate 
scaling  till  the  lupus  elements  are  resorbed,  and  there 
is  left  behind  a  smooth  or  radiating  cicatrix,  it  is  called 
lupus  non  exedens.  Lupus  exedens,  or  rodens,  is  ulcerative. 
4.  Lepra — Elephantiasis  Grcecorum. — Leprosy  formerly 
prevailed  all  over  Europe,  but  is  now  confined  in  that  di- 
vision of  the  globe  to  Iceland,  Norway,  the  northern 

FIG.  231, 


Lupus.  Section  showing  the  transition  of  the  healthy  skin  into  the  highest  degree  of 
infiltration,  a.  Acinous  alveoli,  b.  Germinal  tissue  of  the  lupus  nodule,  c.  Metaplastic 
hair-follicle  and  sebaceous  gland.  1-10.— After  RINDFLEISCH. 

provinces  of  Russia,  and  the  borders  of  the  Caspian  and 
Mediterranean  seas.  It  still  remains  in  Asia  Minor, 
Arabia,  Egypt,  India,  China,  and  the  Hawaiian  Islands. 
It  is  rarely  cured,  and  generally  destroys  life  by  some  sec- 
ondary affection,  as  anaemia,  diarrhoea,  pneumonia,  menin- 
gitis, etc. 

L.  tuberculosa,  the  common  form,  is  characterized  by  a 
nodular  formation  in  the  skin  and  other  organs.  The 
microscope  shows  these  to  consist  usually  of  round  granu- 
lar cells  with  granular  albuminous  intercellular  substance 
(Fig.  232). 

These  nodules  soften  and  form  ulcers,  yielding  a  thin 
sanious  pus,  which  dries  to  a  brownish  crust. 

In  L.  ancesthetica  the  nodules  are  absent,  but  there  is 


THE    MICROSCOPE    IN    PATHOLOGY. 


285 


found  on  the  spinal  cord  a  thick  yellow  dense  mass  of  a 
diffuse  leprous  new  formation,  producing  first  paralysis  of 
sensation,  and  later  of  motion,  with  mummification  and 
necrosis  of  the  skin,  gangrene  of  fingers  and  toes,  etc. 
Sometimes  both  forms  are  combined  in  the  same  patient. 


FIG.  232. 


a.  Lepfa  tissue,  after  Virchow.    Cells  in  division.— After  RINDFLEISCH. 
IV.    PATHOLOGICAL   GROWTHS   OF    EPITHELIAL    ORIGIN. 

1.  Papilloma — Papillary  or  Villous  Tumor. — Papillom- 
ata  are  analogous  to  the  vascular  papillee  of  the  skin, 
villi  of  the  intestine,  etc.,  and  are  composed  of  a  vascular 
connective  tissue  body  or  basis,  covered  with  epithelium 
(Fig.  233). 

They  form  therefore  a  connecting  link  between  the  epi- 
thelial and  connective  tissue  types.  The  quantity  of  epi- 
thelial growth  varies  in  different  papillomata  In  the 
skin  it  is  abundant,  and  the  superficial  layers  are  hard 
and  stratified,  but  in  mucous  membranes  it  is  thinner  and 
softer,  while  in  serous  membranes  it  is  only  a  single  layer. 
Papillomata  of  the  skin  include  warts  and  horny  growths  ; 


286 


THE    MICROSCOPIST. 


those  of  mucous  membranes  are  often  classed  as  mucous 
polypi.  The  latter  occur  on  the  tongue,  in  the  larynx 
and  nose,  on  the  cervix  uteri,  etc.  In  the  bladder  and 
intestine  they  are  very  vascular  and  produce  profuse 


FIG.  233. 


A  hyperplastic  papilla  of  the  cutis,  together  with  epithelium,  from  the  environs  of 
cancroid  of  the  lip. — After  RINDFLEISCH. 


haemorrhage.  Here  they  are  often  mistaken  for  villous 
epithelioma,  since  the  symptoms  are  similar  and  scarcely 
distinguishable  till  after  death.  In  the  papillomata  the 
epithelium  is  homologous,  being  situated  only  on  the  sur- 
face, and  in  no  case  growing  within  the  connective  tissue 
basis.  In  the  epitheliomata  it  is  heterologous  and  is  met 


THE    MICROSCOPE    IN    PATHOLOGY.  287 

with  in  the  subjacent  connective  tissue.  Yet  a  simple 
papilloma  may  develop  into  an  epithelioma. 

2.  Adenoma,  or  Glandular  Tumor. — This  forms  sharply 
defined,  and  generally  encapsuled,  knots  of  new-formed 
glandular  tissue.  Its  structure  resembles  that  of  race- 
mose or  tubular  glands,  and  consists  of  numerous  saccules 
or  tubes  lined  with  squamous  or  cylindrical  epithelial 
cells.  These  are  grouped  together,  being  separated  by  a 
small  amount  of  vascular  connective  tissue. 

As  sarcomata,  myxomata,  etc.,  occurring  in  glandular 
organs,  have  more  or  less  glandular  tissue,  it  is  often  dif- 
ficult to  see  which  predominates,  hence  the  terms  adeno- 
sarcoma,  adeno-myxoma,  etc. 

Adenomata  of  the  skin  vary  in  size  to  that  of  an  egg, 
and  originate  from  sweat  or  sebaceous  glands.  Rlnd- 
fleisch  considers  lupus  to  be  of  this  nature  (see  Lupus). 

Adenomata  of  mucous  membranes  form  mucous  polypi, 
which  are  usually  broad,  rarely  pedunculated,  and  grow 
from  the  size  of  a  bean  to  that  of  a  hen's  egg.  The  sur- 
face of  such  tumors  is  like  that  of  the  mucous  membrane, 
but  internally  it  may  be  fibrous  and  vascular,  or  even 
cystic.  They  occur  on  all  mucous  membranes,  but  often- 
est  in  the  nasal  cavity,  rectum,  and  uterus.  The  conse- 
quences of  these  adenomata  depend  on  their  size  and 
anatomical  relations.  Thus  they  may  form  obstructions 
and  give  rise  to  catarrh  and  haemorrhage. 

Adenomata  of  glands  occur  more  especially  in  the 
mamma,  parotid,  prostate,  liver,  and  thyroid.  Adenoma 
of  the  thyroid  is  known  as  goitre.  Adenoma  of  the 
mamma  (Fig.  234)  is  called  by  Bill  roth  a  "  true  epithelial 
glandular  carcinoma."  The  only  difference  between  it 
and  a  genuine  epithelioma  or  carcinoma  appears  to  be 
that  the  proliferatien  of  the  epithelium  is  confined  to  the 
dilated  glandular  cavities,  instead  of  infiltrating  the  sepa- 
rating walls,  as  in  cancer. 

Some  ovarian  cysts — myxoid   or   colloid  cystomata — 


288  THE    MICROSCOPIST. 

(page  239)  belong  to  the  adenomata.  They  proceed  from 
the  rounded  or  elongated  saccular  epithelial  masses  which 
form  the  processes  of  the  Graafian  follicles. 

Adenomata  are  usually  benign  formations,  but  have  a 
tendency  to  pass  into  cancer. 

3.  Carcinoma,  or  Cancer. — The  term  cancer  is  applied 
to  an  epithelial  new  formation  which  rnay  occur  as  a 
tumor  or  infiltration  in  any  tissue  or  organ,  which  is  quite 


Adenoma  mammae.  Genuine  epithelial  carcinoma  (Billroth).  1-300.— After  RINDFLEISCII. 

malignant,  but  which  is  generally  (not  always)  chronic  in 
its  course.  Its  cells  are  not  peculiar,  being  similar  to 
other  physiological  cells,  but  by  their  rapid  multiplication 
and  metamorphoses  are  followed  by  destruction  of  the 
affected  parts  of  the  organ,  and  finally  of  the  organ  itself. 
It  usually  returns  after  extirpation,  or  it  may  secondarily 
affect  internal  organs.  We  have  seen,  page  264,  that  ma- 
lignancy is  by  no  means  an  exclusive  property  of  cancers, 
since  other  new  formations  may  be  equally  malignant. 

Cancer  occurs  in  various  forms,  as  scirrhus,  encephaloid, 
and  colloid.  Some  consider  epithelioma  also  to  be  a  form 
of  cancer,  but  as  it  is  not  as  malignant  as  other  forms, 
and  is  characterized  by  its  local  growth,  it  may  be  best 
considered  separately  as  cancroid  rather  than  true  cancer. 


THE    MICROSCOPE    IN    PATHOLOGY.  289 

Histologically,  the  forms  of  cancer  resemble  each  other 
in  consisting  of  cells  of  an  epithelial  type,  without  inter- 
cellular substance,  grouped  in  irregular  nests  within  the 
alveoli  of  a  fibroid  stroma  (Fig.  235). 

The  differences  between  various  forms  of  carcinoma 
are  chiefly  dependent  on  the  greater  or  less  proportion  of 
cello  and  fibrous  stroma.  The  deposit  of  pigment,  form- 
ing melanotic  cancer,  as  it  is  termed,  may  also  be  a  cause 

FIG.  235. 


a 

Brushed-out  stroma  of  soft  glandular  cancer,  a.  Section  of  cylinder  of  cancer-cells. 
b.  Trabecuhe  of  the  stroma.  c.  A  single  spindle-cell,  which  extends  from  one  trabecula 
to  another,  and  by  the  separation  of  basis-substance  along  its  protoplasm  gives  the  im- 
pulse to  the  formation  of  a  new  trabecula  of  the  stroma.  d.  Round-celled  infiltrate  in 
the  interior  of  the  trabeculae  of  the  stroma.  1-300.— After  RINDFLEISCH. 

of  variety ;  so  also  ossification  of  the  stroma  (osteoid  cancer) 
and  the  multiplication  and  enlargement  of  the  vessels,  as 
in  fungus  hcematodes ;  but  for  the  purposes  of  study  the 
three  forms  referred  to  are  sufficiently  characteristic. 

A  difference  of  opinion  exists  as  to  the  origin  of  the 
epithelial-like  cells  in  cancers.  Billroth  and  others  regard 
them  as  starting  only  from  pre-existing  epithelium,  while 
Yirchow,  Bindfleisch,  etc.,  consider  that  they  may  be  also 

19 


290 


THE    MICROSCOP1ST. 


derived  from  connective  tissue.  It  is  not  at  all  improba- 
ble that  any  kind  of  bioplasts,  as  Beale  maintains,  may 
form  such  growths  by  rapid  proliferation,  although  the 
weight  of  evidence  justifies  us  in  regarding  epithelial 
structure  as  the  most  frequent  origin.  The  two  follow- 
ing figures  from  Rindfleisch  shows  two  different  forms  of 
origin  in  carcinoma  of  the  liver.  Fig.  236  shows  the  nor- 


FlG.  236. 


Carcinoma  hepatis.  The  production  and  structure  of  pigmented  radiary  cancer.  The 
liver-cell  net  forms  the  first  foundation  of  the  stroma,  while  the  cancer-cells  are  de- 
posited in  the  lumen  of  the  vessels.  1-400.— After  RINDPLEISCH. 

mal  liver-cell  as  furnishing  the  first  foundation  of  the 
strorna,  while  the  cancer-cells  are  found  in  the  vessels. 
The  liver-cells  are  generally  pigmented.  The  spindle- 
formed  and  stellate  cells  which  are  also  seen  in  the  more 
delicate  trabeculse  of  the  stroma  have  nothing  to  do  with 
the  liver-cells.  In  common  cancer  of  the  liver  the  vessels 
form  the  origin  of  the  stroma,  while  the  cancer-cells  come 
from  the  liver-cells  (Fig.  237). 


THE    MICROSCOPE    IN    PATHOLOGY. 


291 


(1.)  Scirrhus. — Hard,  fibrous,  or  chronic  cancer.  This  is 
characterized  by  the  large  amount  of  its  stroma  and  its 
chronic  growth.  At  the  external  surface  of  a  scirrhus 
tumor  the  microscope  shows  cells  of  indifferent,  or  granu- 
lation, tissue  infiltrated  among  the  muscular  or  adipose 
tissue  of  the  part  affected.  At  a  little  greater  distance 
within  these  cells  have  developed  into  nests  of  cancer- 


FIG.  237. 


Carcinoma  hepatis.  The  production  and  structure  of  diffuse  medullary  cancer.  The 
vascular  network  forms  the  first  foundation  of  the  stroraa,  while  the  liver-cells  are  con- 
verted into  cancer-cells,  a.  Normal  liver-cells,  c.  Parenchymatous  inflammation,  b. 
Nests  of  cancer-cells,  v.  Vena  centralis.  1-400. — After  EINDFLEISCH. 

cells,  while  the  interstitial  inflammation  has  produced  an 
abundant  stroma  from  the  growth  of  pre-existent  connec- 
tive tissue,  the  trabeculae  of  which  are  pressed  asunder 
by  the  advancing  cell-formation.  Nearer  the  centre  we 
find  the  cancer-cells  in  a  state  of  retrogressive  metamor- 
phosis, producing  a  diminution  in  the  size  of  the  alveoli, 
and  leading  to  a  puckering  of  the  external  surface  of  the 
tumor.  Fig.  238  exhibits  each  of  these  stages. 


292 


THE    MICROSCOPIST. 


Scirrhus  is  generally  met  with  in  the  mammse  and  in 
the  alimentary  canal.  It  is  quite  hard  previous  to  pass- 
ing into  the  ulcerative  stage,  and  on  section  the  tumor 
exhibits  a  grayish-white  glistening  surface  with  occasion- 
ally fibrous  interlacing  bands.  Scraping  the  juice  from 
such  a  tumor  may  suffice  for  a  cursory  microscopic  exami- 
nation of  its  cells. 

FIG.  233. 


Carcinoma  simplex  mammae,  a.  Development  of  nests  of  cancer-cells.  6.  Fully  formed 
carcinoma  tissue,  c.  Commencing  cicatrization  ;  at  the  same  time  a  representation  of 
the  relations  of  stroma  and  cells  in  scirrhus.  d.  Cancer  cicatrix.  1-300. — After  RIND- 

FLEISCH. 

(2.)  Encephaloid. — Medullary  or  acute  cancer  differs  from 
scirrhus  in  the  rapidity  of  its  growth,  and  consequent 
softness  of  its  structure.  It  is  generally  so  soft  as  to  be 
brainlike,  hence  the  term  encephaloid.  There  are,  how- 
ever, all  intermediate  stages  of  hardness  in  cancers  be- 
tween the  extremes  of  scirrhus  and  encephaloid.  In  the 
latter  epithelial  growth  is  very  rapid,  and  the  proportion 
of  stroma  small,  while  the  abundance  and  softness  of  the 
bloodvessels  produces  frequent  haemorrhages. 

Encephaloid  occurs  generally  in  the  internal  organs  as 
a  secondary  growth  after  extirpation  of  a  cancerous 


THE    MICROSCOPE    IN    PATHOLOGY. 


293 


tumor,  although  it  may  occur  primarily  also,  as  in  the 
articular  ends  of  bones,  in  the  eye,  in  the  testicles,  etc. 

(3.)  Colloid. — Alveolar  or  gelatinous  cancer.  This  form 
depends  on  the  metamorphosis  of  one  of  the  preceding 
forms,  the  cells  of  which  undergo  a  mucoid  or  colloid 
change.  It  is  exceedingly  malignant,  and  may  occur  in 
the  stomach,  large  intestine,  liver,  ovary,  or  mammary 
gland  (Fig.  239). 


Fir.  239. 


Carcinoma  gelatinosum.    1-300. — After  RINDFLEISCH. 

4.  Epithelioma. — Cancroid,  or  epithelial  cancer,  always 
grows  in  connection  \vith  a  cutaneous  or  mucous  surface, 
and  its  epithelial  elements  resemble  the  squamous  variety 
of  epithelium  so  as  scarcely  to  be  distinguished  from  the 
normal  cell.  They  sometimes  have  more  than  one  nu- 
cleus, and  are  often  flattened  and  distorted  by  mutual 
pressure.  They  are  not  so  ready  to  undergo  fatty  degen- 
eration as  the  cells  of  other  varieties  of  carcinoma.  As 
the  cells  multiply  they  have  a  marked  tendency  to  be  ar- 
ranged concentrically  in  groups,  forming  globular  masses 
— "  epithelial  pearls,"  "bird's-nest  bodies,"  etc.  (Fig.  240). 

There  is  little  doubt  as  to  the  epithelial  origin  of  the 


•294 


THE    MICROSCOPIST. 


cells  in  epithelioma.  It  may  be  said  of  this  structure,  as 
well  perhaps  of  all  varieties  of  carcinoma,  that  it  is  com- 
posed of  epithelium  run  mad, — epithelium  become  heterol- 
ogous, — extending  beyond  its  normal  limits  into  subjacent 
tissues.  Epithelioma  is  first  seen  as  a  small  foul  ulcer 
with  indurated  edges,  or  as  an  induration  or  nodule  which 


Section  of  a  cylinder  of  epithelial  cells,  under  a  magnifying  power  of  500.  a.  The 
cylinder  itself,  with  the  characteristic  stratification  of  its  cells,  a  younger  and  an  older 
pearly  globule.  6.  The  stroma,  very  rich  in  cells  at  c,  and  contributing  directly  to  the 
enlargement  by  apposition  of  the  cylinder. — After  RINDFLEISCH. 

subsequent^  ulcerates.  The  surface  of  the  ulcer  is  often 
villous,  and  the  cut  surface  yields  on  pressure  a  small 
quantity  of  turbid  fluid,  or  a  thick  curdy  material  like 
the  sebaceous  matter  of  the  glands  of  the  skin.  This  is 
composed  of  epithelium.  Epithelioma  often  occurs  on 
the  lower  lip  at  the  junction  of  skin  and  mucous  mem- 
brane. It  may  also  grow  on  the  tongue,  scrotum,  etc., 
and  by  its  development  may  involve  any  tissue  whatever. 
Wagner  describes  three  varieties  of  epithelioma :  the 
papillary,  or  warty  pavement-cell  cancer,  whose  surface 


THE    MICROSCOPE    IN    DIAGNOSIS.  295 

is  similar  to  warts  or  pointed  condylomata  ;  cicatricial, 
occurring  usually  in  the  skin  of  the  face  of  old  people  as 
a  superficial  slowly  growing  cancer,  presenting  a  cicatri- 
cial  contraction  of  the  stroma  from  gradual  retrogression 
and  reabsorption  of  the  cells  ;  and  the  mucous  cancroid, 
or  cylindroma,  characterized  by  cylindrical  or  arborescent 
masses  of  mucous  substance. 

The  term  cylindrical  epithelioma  has  been  given  to  those 
forms  which  appear  on  mucous  membranes  with  columnar 
or  cylindric  epithelium.  The  tumors  present  the  same 
epithelial  elements  as  the  tissues  whence  they  grow.  The 
walls  of  the  alveoli  show  columnar  epithelium,  so  that 
the  distinction  between  such  tumors  and  simple  adenom- 
ata is  very  difficult.  A  variety  of  this  form  occurs  as  a 
villous  growth  on  mucous  membranes,  as  the  bladder, 
uterus  (cauliflower  excrescence),  and  stomach. 


CHAPTER    XIV. 

THE    MICROSCOPE    IN   DIAGNOSIS. 

IN  diagnosis  the  microscopical  observer  is  necessarily 
confined  to  an  examination  of  the  various  fluids  and  dis- 
charges of  the  body.  Dr.  Pritchard's  microscope  for  ex- 
amining the  circulation  of  blood  in  the  frseiwm  of  the 
human  tongue,  described  by  Dr.  Beale,  is  an  ingenious 
attempt  to  investigate  the  actual  condition  of  the  living 
subject,  and  indicates  a  direction  which  may  hereafter  be 
profitably  pursued,  but  as  yet  is  too  refined  for  the  pur- 
poses of  the  practical  student. 

I.    THE    BLOOD   IN    DISEASE.' 

The  normal  structure  of  blood  has  been  sufficiently  de- 
scribed at  page  186.  It  remains  now  to  point  out  briefly 


296  THE    MICROSCOPIST. 

the  methods  of  examination  and  considerations  useful  in 
diagnosis. 

The  presence  of  too  large  a  proportion  of  white  corpus- 
cles (leucocytes)  in  the  blood  constitutes  what  is  known 
as  leucaemia,  and  is  usually  associated  with  morbid  changes 
in  the  spleen  and  lymphatic  glands.  But  the  relative 
numbers  of  white  and  red  corpuscles  vary  in  different 
persons,  at  different  times,  and  in  different  morbid  states, 
so  that  great  care  is  needed  in  forming  an  opinion.  Thus 
in  anaemic  and  cancerous  patients  the  proportion  of  white 
corpuscles  is  increased. 

Prick  the  skin  of  the  finger  with  a  needle  after  moderate 
compression,  and  place  the  drop  of  blood  thus  obtained  on 
a  perfectly  clear  slide,  and  cover  with  thin  glass  in  the 
usual  way.  No  more  blood  should  be  taken  than  is  suffi- 
cient to  fill  the  capillary  space  between  the  slide  and  cover. 
The  white  corpuscles  in  the  field  of  the  microscope  should 
then  be  counted,  or  an  estimate  made  of  the  proportion 
of  white  to  red  corpuscles. 

Several  "fields"  should  be  averaged  before  arriving  at 
an  opinion.  This  is  but  a  rough  method,  and  for  more 
accurate  determination  a  variety  of  tubes  and  slides  have 
been  devised.  The  capillary  apparatus  of  Dr.  Malassez 
is  so  constructed  that  one  volume  of  blood  diluted  with 
one  hundred  volumes  of  a  ten  per  cent,  solution  of  sul- 
phate of  soda,  to  facilitate  enumeration  and  prevent  co- 
agulation, is  placed  in  a  capillary  tube  adjusted  on  a  glass 
slide  so  as  to  indicate  a  definite  cubic  capacity  for  a  given 
length,  which  relation  is  marked  on  the  slide  by  the  in- 
strument-marker. Then,  by  means  of  an  eye-piece  mi- 
crometer, divided  into  squares,  the  actual  number  of  cor- 
puscles, white  and  red,  can  be  counted,  and  on  multiplying 
by  one  hundred  for  the  dilution  used,  we  have  the  figure 
desired.  Hayem  and  Nachet  employ  a  slide  having  a 
glass  ring  one-fifth  of  a  millimeter  in  depth  cemented  on 
it.  A  drop  of  blood  diluted  as  above  is  placed  in  the  cell 


THE    MICROSCOPE    IN    DIAGNOSIS.  297 

and  covered  with  a  flat  glass  cover.  As  soon  as  the  cor- 
puscles have  settled  to  the  bottom,  the  number  in  a  defi- 
nite area  is  counted.  If  the  area  chosen  is  one-fifth  of  a 
square  millimeter,  we  have,  of  course,  one-fifth  of  a  cubic 
millimeter  of  diluted  blood  ready  for  enumeration  by  aid 
of  the  ocular  micrometer  divided  into  squares  as  before. 

Changes  in  the  appearance  of  the  globules,  white  or 
red,  should  be  noted,  even  though  such  changes  are  due 
to  physical  causes,  as  crenated  margins,  not  running  to- 
gether in  rouleaux,  etc.  Minute  particles  of  bioplasm  (mi- 
crocy  tes)  are  sometimes  seen,  appearing  as  granular  debris, 
whose  significance  is  unknown.  In  pernicious  anaemia 
globular  cells,  deeper  in  color  and  smaller  than  ordinary 
red  globules,  have  been  observed.  In  a  case  reported  by 
Dr.  Mackenzie  the  number  of  red  disks  was  but  18.6  per 
cent,  or  930,000  to  the  cubic  millimeter,  instead  of  5,000- 
000  (page  187). 

In  the  disease  known  as  malignant  pustule,  splenic 
fever,  anthrax,  etc.,  a  short,  straight,  motionless  rod, 
about  as  long  as  the  width  of  a  blood-corpuscle,  has  been 
found  in  the  blood,  and  is  definitely  related  to  the  activity 
of  the  virus.  It  is  called  Bacillus  anthracis,  and  resembles 
a  common  and  harmless  one  found  in  infusions  of  hay, 
etc.,  the  Bacillus  subtilis,  although  the  latter  is  endowed 
with  motion. 

In  relapsing  fever,  during  the  paroxysm  and  relapse, 
but  not  in  the  interval,  Spirilla  are  found  in  the  blood. 
They  are  minute  spirals  of  great  tenuity,  and  are  from 
two  to  six  times  the  breadth  of  a  blood-corpuscle. 

The  Filaria  sanguinis  hominis  is  found  in  the  blood  and 
urine  of  persons  affected  with  a  certain  form  of  chyluria. 
It  is  about  the  breadth  of  a  blood-cell,  and  ^gth  of  an 
inch  in  length.  It  exhibits  active  wriggling  movements.* 

*  Finlayson's  Clinical  Diagnosis. 


298  THE    MICROSCOPIST. 

Dr.  Cobbold  states  that  its  larval  state  is  passed  in  the 
stomach  of  the  mosquito. 

Dr.  Beale  has  found  cells  similar  to  white  corpuscles, 
but  larger,  in  cases  of  cholera  and  of  pyaemia.  Many  of 
these  were  too  large  to  pass  the  capillaries. 

The  tendency  of  cells  to  adhere  is  thought  by  Beale  to 
depend  on  a  reduction  of  the  amount  of  water.  He  ob- 
served such  tendency  to  be  increased  after  watery  evacua- 
tions by  Epsom  salts. 

Dr.  Coupland  described  corpuscles,  of  a  red  color,  ^^th 
of  an  inch  in  diameter  in  blood  from  a  case  of  Addison's 
disease.  They  disappeared  as  the  patient  improved. 

Dr.  Lostorfer,  of  Vienna,  professed  to  be  able  to  distin- 
guish syphilitic  blood  by  the  presence  of  peculiar  bright 
bodies  in  from  one  to  five  days  after  it  had  been  taken 
from  the  patient.  The  drop  of  blood  on  a  slide,  covered 
with  thin  glass,  is  placed  under  a  bell-glass  arranged  as  a 
moist  chamber.  In  from  one  to  five  days,  in  addition  to 
vibriones,  bacteria,  and  sometimes  sarcina,  there  appeared 
these  bright  bodies,  some  at  rest  and  some  vibratile. 
Many  of  the  larger  ones  were  seen  to  increase  by  budding. 
He  calls  them  syphilitic  corpuscles. 

Epithelial  elements  from  the  lining  of  the  bloodvessels 
have  been  seen  in  the  blood.  Cancer-cells  may  in  this 
way  be  transferred  to  distant  parts.  Epithelial  cells  be- 
coming impacted  in  the  smaller  vessels  may  give  rise  to 
thrombosis  and  abscesses,  as  in  puerperal  and  pysemic 
fever. 

Dr.  Beale's  researches  upon  the  cattle-plague  led  him 
to  believe  that  particles  of  germinal  matter  (contagium) 
introduced  from  without  into  diseased  blood,  and  the 
products  of  their  decay,  may  give  rise  to  local  congestions 
and  various  eruptions,  as  boil,  carbuncle,  and  pustule. 

Dr.  Salisbury  thinks  that  rheumatism  may  be  detected 
long  before  the  appearance  of  active  symptoms  by  the 
excess  of  fibrin  deposited  in  a  drop  of  blood.  He  states 


THE    MICROSCOPE    IN    DIAGNOSIS.  299 

that  cholesterin  or  nerve-fat  may  be  seen  in  blood  which 
has  been  kept  from  one  to  three  days,  and  that  variations 
in  this,  seen  under  the  microscope,  may  throw  light  upon 
disordered  mental  and  nervous  functions.  He  claims  that 
carbuncle,  intermittent  fever,  enteric  fever,  and  small-pox 
are  produced  by  fungi  in  the  blood,  which  he  names  re- 
spectively Crypta  carbunculata,  Gemiasma  viridis,  Byoly- 
sis  typhoides,  and  Ivy  variolosa. 

The  examination  of  blood  in  disease  requires  patient 
care  and  the  employment  of  high  powers,  not  less  than 
1000  diameters.  As  a  field  for  original  investigation,  this 
subject  affords  a  most  tempting  opportunity  to  those  who 
have  the  leisure  and  skill  to  pursue  it.  The  time  may 
come  when  more  may  be  known  of  a  patient's  disease  by 
an  examination  of  a  drop  of  blood  under  the  microscope 
than  is  possible  in  any  other  way. 

In  medico-legal  inquiries  the  decision  whether  a  blood- 
stain is  of  human  blood  or  of  one  of  the  lower  animals  is 
one  requiring  exceptional  skill,  if,  indeed,  it  is  at  all 
practicable.  The  differences  given  on  page  187  are  easily 
enough  seen,  but  the  red  disks  in  a  dog,  a  rabbit,  etc.,  so 
nearly  approach  those  of  human  blood  in  size,  and  the 
appearance  of  corpuscles  in  the  same  drop  varies  so  much 
under  high  powers,  as  to  lead  to  doubtful  testimony  before 
a  jury.  Dr.  J.  G.  Richardson  believes  it  quite  possible  to 
distinguish  human  blood,  but  at  present  few  microscopists 
agree  with  him.  In  a  doubtful  case  it  would  be  well  to 
scrape  off  from  the  slide  half  of  the  drop  of  suspected 
blood,  replace  it  with  undoubted  human  blood,  and  pho- 
tograph the  disks,  so  that  one-half  in  the  field  of  view 
would  be  known  and  ready  for  comparison  with  the  other 
half. 

To  detect  the  red  corpuscles  in  a  blood-stain,  it  is  well 
to  soften  the  clot  with  glycerin  diluted  with  water  to  the 
specific  gravity  of  serum,  or  a  one  per  cent,  solution  of 
salt  may  be  used.  If  this  fails,  an  attempt  may  be  made 


300  THE    MICROSCOPIST. 

to  obtain  haemin  crystals.  A  portion  of  the  supposed 
blood-clot  is  placed  on  the  slide,  and  a  drop  of  water  con- 
taining a  trace  of  salt  is  added.  A  thin  glass  cover  is 
applied,  and  a  little  glacial  acetic  acid  is  allowed  to  flow 
in  and  mix  with  the  blood.  Heat  is  applied  until  the 
mixture  almost  boils.  The  slide  is  then  placed  under  the 
microscope,  and  the  rhomboidal  crystals  may  be  observed 
with  a  J-inch  objective. 

For  microspectroscope  appearances,  etc.,  see  page  102. 
The  guaiacum  test,  as  it  is  called,  depends  upon  the  ozone 
of  the  hsemaglobulin  of  the  blood  causing  a  bluish  tint 
in  the  solution  of  guaiacum.  The  tincture  is  made  by 
dissolving  one  part  of  the  resin  in  six  parts  of  alcohol  of 
eighty  per  cent.  The  bottles  are  to  be  only  half  filled,  so 
that  the  tincture  may  be  in  contact  with  the  air.  Strips 
of  white  blotting-paper  are  soaked  in  this  and  the  alcohol 
allowed  to  evaporate.  A  weak  solution  of  blood  dropped 
on  the  paper  produces  a  blue  color.  This  is  only  valuable 
as  a  negative  test,  since  other  substances  give  the  same 
reaction.  If  no  color  is  obtained,  blood  is  not  present. 

II.    EXAMINATION   OF    URINE. 

Healthy  urine  contains  a  variety  of  organic  and  inor- 
ganic substances,  as  urea,  uric  acid,  alkaline  and  earthy 
salts,  animal  extractive,  vesical  mucus,  and  epithelial 
debris.  A  drop  or  two  evaporated  on  a  glass  slide  will 
show  the  crystalline  matters,  consisting  of  urea,  urate  of 
soda,  chloride  of  sodium,  phosphates,  and  sulphates. 

Before  examining  urine  for  the  purpose  of  diagnosis,  it 
is  necessary  to  be  familiar  with  the  appearance  of  the 
contents  of  healthy  urine,  as  well  as  of  accidental  sub- 
stances which  are  likely  to  be  met  with,  as  fragments  of 
hair,  wool,  feathers,  cotton,  silk,  and  flax,  particles  of 
starch,  breadcrumbs,  sand,  vegetable  fibres,  etc.  Igno- 


THE    MICROSCOPE    IN    DIAGNOSIS.  301 

ranee  of  the  microscopic  appearance  of  these  common 
things  has  led  to  ludicrous  mistakes. 

The  amount  of  urine  passed  in  each  twenty-four  hours 
varies  from  20  to  50  ounces,  holding  in  solution  from  600 
to  700  grains  of  solid  matter.  The  amount,  both  of  solids 
and  fluids,  varies  according  to  the  amount  of  fluids  im- 
bibed, the  action  of  the  skin,  etc.  The  quantity  of  urine 
should  be  considered  in  relation  with  its  specific  gravity, 
since  diminished  urine  with  greater  specific  gravity  may 
occur  in  diarrhoea,  etc.,  and  imbibed  fluids  may  cause 
greater  quantities  with  lessened  specific  gravity. 

The  average  specific  gravity  of  healthy  urine  is  1.020. 
It  may  be  measured  by  means  of  the  specific  gravity  bot- 
tle, or  with  the  urinometer,  a  loaded  glass  bulb  with 
graduated  stem.  According  to  Dr.  G.  Bird,  each  degree 
of  the  urinometer  represents  2.33  grains  of  solids  in  1000. 
Thus  specific  gravity  1.020  represents  46.60  grains  solid 
matter,  and  953.40  water  in  1000  of  urine. 

Another  table  of  Dr.  Bird's  shows  that  the  specific 
gravity  figures  indicate  nearly  the  amount  of  solids  in 
each  fluid  ounce.  Thus  1010  shows  10  grains  of  solids, 
1020  about  20  grains,  etc.  Yet  this  is  only  approximate. 

High  specific  gravities  (above  1025)  are  found  in  dia- 
betes (from  sugar),  in  concentrated  urine  from  fevers  or 
other  causes,  in  acute  renal  dropsy,  and  sometimes  from 
large  quantities  of  albumen  in  solution.  Low  specific 
gravities  (below  1015)  occur  when  the  quantity  is  exces- 
sive, especially  in  diabetes  insipidus,in  lardaceous  disease 
of  the  kidney,  and  chronic  cases  of  Bright's  disease. 

UREA. 

Urea  is  the  vehicle  by  which  nearly  all  the  nitrogen  of 
the  exhausted  tissues  is  removed  from  the  system,  and 
its  retention  is  often  attended  with  fatal  ursemic  poison- 
ing of  the  blood.  The  quantity  naturally  eliminated  de- 


302  THE    MICROSCOPIST. 

pends  largely  upon  the  amount  taken  in  as  food,  but  may 
be  stated  generally  as  from  400  to  500  grains  a  day,  or 
3J  grains  per  pound  weight  of  the  body.  The  specific 
gravity  of  the  urine  usually  gives  an  indication  of  the 
quantity  of  urea  excreted,  since  it  is  about  one-third  of 
the  amount  of  solid  matter. 

If  urea  be  suspected  in  excess,  a  drop  of  urine  (concen- 
trated and  cold)  may  be  put  on  a  slide  and  a  drop  of  nitric 
acid  added.  On  covering  with  thin  glass  and  placing 
under  J-inch  objective,  the  characteristic  rhomboidal  crys- 
tals of  nitrate  of  urea  will  be  seen  (Plate  XXVI,  Fig. 
240). 

Volumetric  analysis  is  the  best  means  of  ascertaining 
the  quantity  of  urea  as  of  other  chemical  ingredients,  but 
this  falls  rather  within  the  province  of  the  professional 
chemist  than  of  the  microscopist.  The  practitioner  may 
estimate  approximately  by  weighing  the  crystals  of  nitrate 
of  urea  formed  by  adding  nitric  acid  to  double  the  quan- 
tity of  urine  \vhich  has  been  concentrated  to  half  its  bulk. 

CHLORIDES. 

The  chlorides  are  always  present  in  normal  urine.  They 
are  diminished,  and  sometimes  nearly  suppressed,  in  sev- 
eral febrile  diseases,  especially  in  pneumonia.  The  quan- 
tity may  be  roughly  estimated  by  acidulating  the  urine 
with  a  few  drops  of  nitric  acid,  and  then  adding  a  strong 
solution  of  nitrate  of  silver.  The  density  or  abundance 
of  the  precipitate,  as  compared  with  a  sample  of  normal 
urine,  indicates  the  quantity;  or  the  precipitate  maybe 
weighed  after  being  dried  and  fused  in  a  porcelain  capsule. 
Albumen,  if  present,  must  be  separated  before  testing  for 
chlorides,  as  it  is  also  thrown  down  by  nitrate  of  silver. 


PLATE  XXVI. 


FIG.  240. 


£._/ 


CVyX^-00 

Qj\  O     £7/s, 

I'A  ^g/     (.J 

Q 
Nitrate  of  Urea. 

FIG.  242. 


V 


Urate  of  Ammonia. 


FIG.  244. 


Uric  Acid. 


FIG.  241. 


Tube-casts. 


FIG.  243. 


Uric  Acid. 


FIG.  245. 


Uric  Acid— re-precipitated. 


THE    MICROSCOPE    IN    DIAGNOSIS.  303 


BILE. 

Bile  in  urine,  if  present  in  large  quantity,  can  be  recog- 
nized by  the  eye.  In  testing  for  albumen  by  nitric  acid, 
the  greenish  color  produced  by  bile  will  also  attract  notice. 
A  more  delicate  test  consists  in  placing  a  drop  or  two  of 
urine  and  a  drop  or  two  of  strong  nitric  acid  near  together 
on  a  white  plate  and  allowing  one  to  run  into  the  other. 
As  the  acid  mixes  with  the  fluid,  a  play  of  colors,  com- 
mencing in*  green  and  terminating  in  red,  passing  through 
various  shades,  will  be  observed. 

Bile  in  urine  indicates  jaundice,  and  may  aid  in  the 
differential  diagnosis  of  discolorations  of  the  skin  and 
conjunctiva  due  to  other  causes.  It  may  show  an  incipi- 
ent jaundice  before  the  tissues  are  generally  affected,  and 
its  disappearance  may  afford  evidence  that  the  attack  is 
passing  off  when  the  effects  of  jaundice  may  be  visible 
elsewhere. 

ALBUMEN. 

In  suspected  albuminuria,  samples  should  be  examined 
which  were  passed  at  different  times  of  the  day,  as  before 
eating  in  the  morning,  and  after  eating  in  the  evening. 
Care  should  be  taken  to  have  clean  bottles,  test-tubes,  etc. 
The  urine  should  be  subjected  to  a  double  test,  by  boiling 
in  a  test-tube  and  the  subsequent  addition  of  a  drop  or 
two  of  nitric  acid,  and  by  the  addition  of  strong  nitric 
acid  to  a  separate  portion  of  the  cold  urine.  In  the  latter 
test  a  cloudy  ring  of  albumen  appears  at  the  junction  of 
the  two  fluids. 

The  quantity  of  albumen  may  be  estimated  sufficiently 
for  clinical  practice  by  allowing  the  precipitate  formed  on 
boiling  to  subside  for  a  definite  time, — twelve  to  twenty- 
four  hours, — and  observing  how  much  of  the  tube  is  occu- 
pied, as  a  half,  a  fourth,  an  eighth,  etc. 


304  THE    MICROSCOPIST. 

Sometimes  albumen  is  due  to  the  presence  of  blood,  pus, 
etc.,  as  revealed  by  the  microscope,  and  its  significance 
must  be  considered  under  these  terms.  Many  acute  febrile 
diseases  give  rise  to  albuminuria,  which  may  be  regarded 
as  one  feature  of  the  general  disturbance  rather  than  of 
local  importance. 

After  the  primary  fever  of  scarlatina,  and  occasionally 
after  small-pox,  enteric  fever,  and  erysipelas,  albuminuria 
is  present.  It  is  not  infrequent  in  pregnancy  and  the 
puerperal  state,  and  though  not  necessarily,  yet  often  in- 
dicates possible  danger  of  convulsions  during  labor,  chronic 
renal  disease,  etc. 

Chronic  chest  complaints  are  often  complicated  with 
albuminuria,  which  has  an  important  bearing  on  progno- 
sis. In  such  cases  it  may  be  only  one  of  the  indications 
of  a  temporary  general  venous  congestion,  or  it  may  indi- 
cate a  nephritis  established  through  long-continued  con- 
gestion, or  the  renal  disease  shown  by  the  albuminuria 
may  be  primary  and  the  thoracic  affection  a  complication. 
In  all  dropsies  the  presence  of  albumen  is  important. 
Genuine  renal  dropsy  rarely  occurs  without  it,  yet  it  may 
be  secondary  and  due  to  pressure  on  the  renal  veins 

Albuminuria  in  acute  or  chronic  renal  disease  must  be 
considered  in  connection  with  other  urinary  contents,  as 
tube-casts,  epithelium,  etc.,  and  with  alterations  in  quan- 
tity, specific  gravity,  etc. 

The  significance  of  albuminuria  in  nervous  diseases  is 
variable.  It  may  be  an  effect  of  nervous  disturbance,  as 
after  a  convulsion  or  from  some  lesion  of  the  brain,  or  the 
renal  disease  may  be  the  cause  of  the  nervous  affection, 
as  in  urcemic  coma  or  convulsions,  etc. 

We  must  look  for  albumen  in  the  urine  in  many  chronic 
and  constitutional  affections,  and  transiently  after  the  use 
of  blisters,  etc.  Where  there  are  so  many  sources  of 
albuminous  urine  we  must  be  guided  by  the  general 
symptoms,  and  particularly  the  presence  of  microscopic 


THE    MICROSCOPE    IN    DIAGNOSIS.  305 

deposits,  derangements  of  quantity,  and  density  in  the 
urine. 

SUGAR. 

Urine  should  be  tested  for  sugar  when  diabetes  is  sus- 
pected, or  when  the  quantity  is  excessive,  or  the  specific 
gravity  is  high  (above  1030).  In  some  cases  of  cerebral 
disease,  also,  sugar  appears  in  the  urine.  The  urine  should 
first  be  examined  for  albumen,  since  its  presence  is  a  serious 
complication  of  diabetes,  and  it  may  interfere  with  the 
reactions  by  the  copper  test.  If  present  it  should  be  re- 
moved by  boiling  and  filtration.  Boiling  albuminous  urine 
with  crystals  of  sulphate  of  soda  is  said  to  render  it  suit- 
able for  the  copper  test,  but  the  other  way  is  best. 

Copper  Test — Trommer's  Test. — The  urine  is  mixed  with 
a  few  drops  of  a  solution  of  sulphate  of  copper  in  a  test- 
tube;  excess  of  liquor  potassee  is  then  carefully  added, 
enough  to  just  dissolve  the  precipitate  it  first  throws 
down ;  the  mixture  is  then  boiled,  and  if  sugar  is  present 
a  red  precipitate  of  suboxide  falls  down.  As  errors  occur 
from  not  using  the  proper  proportions,  the  following  test 
is  preferred: 

Fehling's  Test  Solution.—  Sulphate  of  copper,  90 J  grains ; 
neutral  tartrate  of  potash,  3tf4  grains;  solution  of  caustic 
soda  (of  specific  gravity  1.12),  4  fluid  ounces;  add  water 
to  make  up  6  fluid  ounces.  (Or  40  grams  of  sulphate  of 
copper  in  crystals,  160  grams  neutral  tartrate  or  potash, 
750  grams  caustic  soda,  specific  gravity  1.12;  add  water 
up  to  1154.5  cubic  centimeters.  Each  10  cubic  centimeters 
correspond  to  0.05  gram  of  grape-sugar.) 

A  little  of  the  test  fluid  is  first  boiled  in  a  test-tube  to 
see  if  it  remains  unchanged  in  color,  since  it  is  apt  to  alter 
by  age.  If  unaffected,  add  a  drop  or  two  of  the  suspected 
urine.  If  sugar  be  present  in  quantity  the  color  changes, 
and  a  yellowish  or  reddish  precipitate  falls.  If  no  reac- 
tion occurs,  add  a  little  more  urine,  but  less  than  the 

20 


306  THE    MICROSCOPIST. 

volume  of  test  fluid,  boil  it  and  cool;  if  no  yellow  or  red 
suboxide  falls,  it  is  free  from  sugar.  Prolonged  boiling 
must  be  avoided,  as  well  as  boiling  the  urine  before  add- 
ing the  test. 

To  determine  the  quantity  of  sugar  by  the  copper  test 
Fehling's  solution  is  made  of  such  strength  that  200  grains 
(by  measure)  are  completely  reduced  by  one  grain  of  dia- 
betic sugar.  The  test  fluid  is  boiled  in  a  flask,  etc.,  and 
a  quantity  of  pure  water  equal  to  one  or  two  volumes  of 
test  fluid  poured  in  also.  The  saccharine  urine,  diluted 
with  one  volume  urine  to  nine  of  water  if  suffar  is  abun- 

Z3 

dant,  is  placed  iu  a  burette,  graduated  to  grains,  and  is 
gradually  added  to  the  boiling  copper  solution  till  the 
blue  color  is  quite  discharged.  The  number  of  grains  of 
urine  consumed — representing  one  grain  of  sugar — is 
read  off,  and  it  is  then  a  matter  of  calculation  how  many 
grains  are  contained  in  the  ounce  of  urine,  making  allow- 
ance for  the  degree  of  dilution. 

fermentation  Test. — This  is  sometimes  more  convenient 
or  preferred  from  uncertain  results  of  the  copper  test.  A 
small  tube  is  filled  with  suspected  urine,  a  little  fluid  or 
solid  (German)  yeast  is  added,  and  the  tube  is  inverted 
over  a  saucer  containing  urine  and  placed  in  a  warm  situ- 
ation for  twenty -four  hours.  If  sugar  is  present  it  under- 
goes fermentation,  yielding  alcohol  and  carbonic  acid. 
The  latter  rises  in  the  tube  and  displaces  the  liquid.  The 
quantitative  test  by  fermentation  consists  in  determining 
the  specific  gravity  of  the  urine  before  and  after  complete 
fermentation.  It  has  been  found,  empirically,  that  one 
degree  of  specific  gravity  lost  by  fermentation  corre- 
sponds with  one  grain  of  sugar  per  fluid  ounce  of  urine. 

Bismuth  Test. — Mix  an  equal  volume  of  suspected  urine 
with  a  solution  of  carbonate  of  soda — one  part  of  the 
crystals  to  three  parts  water  (or  with  half  as  much  liquor 
potassae).  Put  in  a  little  basic  nitrate,  or  subnitrate  of 
bismuth,  and  boil.  If  sugar  be  present  the  bismuth  be- 


THE    MICROSCOPE    IN    DIAGNOSIS.  307 

comes  grayish  or  blackish  from  the  formation  of  the  sub- 
oxide  or  of  metallic  bismuth. 

URINARY    DEPOSITS. 

Deposits  from  urine  are  either  organic  or  precipitates 
from  solution.  The  urine  should  be  put  in  a  conical  glass 
of  four  or  five  ounces  capacity,  and  kept  free  from  dust 
for  about  twelve  hours.  A  small  portion  of  the  sediment 
should  then  be  taken  up  with  a  clean  pipette  and  ex- 
amined under  the  microscope  on  a  glass  slide  covered  in 
the  usual  way  (page  77).  A  quarter  of  an  inch  objective 
will  be  found  most  generally  useful. 

To  facilitate  microscopical  examination  and  diagnosis 
we  add  the  following  table  from  Richardson's  Medical 
Microscopy  : 

I.  A  distinct  deposit  is  seen  in  the  urine. 

A.  This  deposit  is  light  and  flocculent. 

a.  It  occurs  in  albuminous  urine,  one  yielding  a  coagu- 
lum  with  heat,  and  nitric  acid. 

a.  The  microscope  shows  casts  of  the  uriniferous  tubules 
(transparent  or  granular  cylinders  ^-g-th  to  ^-^ih  of  an 
inch  in  diameter),  either  granular,  epithelial,  or  hyaline, — 
Bright' 's  disease  of  the  kidney. 

p.  The  microscope  shows  red  blood-corpuscles  (non-nu- 
cleated disks  35V<jth  of  an  inch  in  diameter),  mixed  with 
mucus, — hcematuria. 

y.  Leucocytes  only  are  seen  (nucleated  corpuscles, — pus- 
corpuscles, — jjsg-Q-th  of  an  inch  in  diameter), — nephritis, 
cystitis,  etc. 

b.  The  urine  is  not  albuminous. 

a.  Leucocytes,  epithelial  cells  from  the  bladder,  and  per- 
haps mucous  casts  of  the  tubules  appear, — irritation  of 
urinary  tract. 

P.  Spermatozoa, — if  numerous,  spermatorrhoea, 
Y-  Fungous  growths  (cellular  bodies  ^Vo^1  to 


308  THE    MICROSCOriST. 

of  an  inch  in  diameter,  often  arranged  in  chains,  still,  or 
vibratile), — pathological  significance  uncertain. 

d.  Hyaline  and  pale  tube-casts  (rare  in  non-albuminous 
urine), — Bright9 s  disease. 

B.  Deposit  dense,  opaque,  bulky. 
a.  Urine  non-albuminous. 

a.  Microscopic  deposit,  granular  simply, — urates  or  phos- 
phate of  lime.     The  former  dissolve  on  heating. 

ft.  Microscopic  crystals,  triangular  prisms  and  their  de- 
rivatives,— triple  phosphates. 

b.  Urine  albuminous. 

«.  Leucocytes  only, — nephritis,  cystitis,  etc. 
ft.  Crystals   of    triple   phosphates,   with   leucocytes, — 
chronic  cystitis,  perhaps  calculus. 

C.  Deposit  granular  or  crystalline;  small. 
a.  Urine  albuminous. 

a.  Red  blood-disks, — h&maiuria. 

ft.  Cancer-cells  (irregular,  caudate,  and  oval,  with  large 
nuclei), — carcinoma.  Mistake  not  epithelial  for  cancer 
cells. 

f.  Tubercle  corpuscles  (non-nucleated,  granular,  oval 
bodies,  about  j^^thof  an  inch  in  diameter), — tuberculosis. 

b.  Urine  not  albuminous. 

a.  Oxalate  of  lime  crystals  (brilliant  octohedra,  show- 
ing as  squares  marked  with  diagonal  crosses,  or  more 
rarely  as  dumb-bells), — oxaluria. 

ft.  Uric  acid  crystals  (yellowish,  lozenge-shaped,  oval, 
barrel-shaped ,  e tc . ) , — lithuria . 

Y  Microscopic  spherules  and  dumb-bells,  soluble  in 
acetic  acid  with  effervescence, — carbonate  of  lime. 

S   Hexagonal  crystals  of  cystin, — cystinuria. 

e.  Sediment  resembling  uric  acid,  but   soluble  in  hot 
water  and  mineral  acids, — xanthin. 

C.  Sheaflike  bundles  or  globular  masses  of  acicular  crys- 
tals, tyrosin  and  leucin, — acute  atrophy  of  liver? 
f).  Hydatids,  etc., — entozoa. 


THE    MICROSCOPE    IN    DIAGNOSIS.  309 

II.  Urine  turbid,  without  distinct  deposit. 

A.  Turbidity    disappears     on     warming,  —  amorphous 
urates. 

B.  Cloudiness  remains  while  heating. 

«.  Yibriones  and  bacteria  present, — putrefactive  fermen- 
tation. 

p.  Numerous  minute  molecules, — chylous  urine. 

III.  A  film  on  surface  of  urine. 

A.  Prisms  of  triple  phosphates,  usually  with  granular 
phosphates  and  spherules  of  urate  of  soda, — phosphuria. 

B.  Numerous  small  oil-globules,  with  triple  phosphates, 
— kiestin. 

EPITHELIUM. 

The  character  of  the  epithelial  scales  will  often  show 
the  locality  of  disease  in  the  urinary  tract  (Fig.  142). 
JRenal  epithelium,  lying  loose  in  the  deposit  is  somewhat 
globular,  and  may  sometimes  be  compared  with  that  in 
the  tube-casts  in  the  same  specimen  It  bears  quite  a  re- 
semblance to  pus-cells.  It  occurs  in  desquamative  nephri- 
tis, and  undergoes  various  changes,  appearing  atrophied, 
granular,  or  fatty.  Sometimes  large  granular  corpuscles 
occur  with  fatty  epithelium,  being  altered  cells  them- 
selves. 

Cells  from  the  bladder  occur  often  as  groups  of  tessellated 
cells  of  circular  form — sometimes  pyramidal.  Caudate 
epithelium  is  found  in  the  ureter  and  pelvis  of  the  kidney, 
and  may  be  caused  by  calculous  pyelitis.  Large  scaly 
epithelium  comes  from  the  vagina. 

MUCUS    AND   PUS. 

Mucus  is  deposited  as  a  flocculent  cloud,  entangling  a 
few  round  or  oval  delicately  granular  cells,  a  little  larger 
than  a  red  blood-globule.  In  disease  this  increases  and 
contains  numerous  ill-defined  cells.  A  very  thick  glairy 


310  THE    MICROSCOPIST. 

deposit  in  disease  of  the  bladder  may  be  mistaken  for 
mucus  when  it  is  pus  altered  by  the  action  of  carbonate  of 
ammonia. 

Pus  is  formed  often  from  the  germinal  matter  of  epi- 
thelium, so  that  a  small  quantity  in  urine  is  not  neces- 
sarily a  sign  of  serious  disease.  In  large  quantities  pus 
forms  an  opaque  cream-colored  deposit,  which  becomes 
glairy  and  tenacious  by  the  addition  of  liquor  potassae. 
The  addition  of  the  latter  will  dissolve  white  urates,  and 
serves  to  distinguish  pus  from  them  as  well  as  from  phos- 
phates, which  are  little  affected  by  it.  The  microscope, 
however,  is  the  best  test. 

Purulent  urine  is  usually  acid  if  of  renal  origin  (if  tested 
immediately),  and  is  alkaline  and  ammoniacal  in  suppura- 
tion from  the  bladder.  Coexisting  epithelium,  etc.,  is 
often  of  value  in  determining  the  origin  of  pus.  Pus- 
globules  under  the  microscope,  if  long  removed  from  the 
body,  are  granular  and  show  from  one  to  four  nuclei  when 
treated  with  acetic  acid.  In  fresh  pus-corpuscles,  espe- 
cially in  warm  weather,  amoeboid  motion  is  often  seen. 
In  a  late  period  of  catarrh  of  the  bladder  but  little  epi- 
thelium may  accompany  the  discharge,  but  crystals  of 
triple  phosphates  occur  generally  in  pus  derived  from  the 
bladder. 

The  clinical  significance  of  pus  in  the  urine  is  quite 
varied.  It  may  follow  renal  inflammation,  and  often  ap- 
pears in  alburninuria  following  fevers  and  in  renal  em- 
bolism. Abscesses  opening  into  the  urinary  tract,  cysti- 
tis, cancer  of  the  bladder,  suppuration  of  the  prostate, 
gonorrhoea,  and  gleet  may  all  give  rise  to  purulent  urine. 
Accidental  mixture  from  lochial  or  leucorrhoeal  discharges 
is  also  possible. 

BLOOD. 

Blood  may  sometimes  be  recognized  by  the  eye  in  urine 
from  its  smoky  or  dingy  tint,  especially  in  blood  from  the 


THE    MICROSCOPE    IN    DIAGNOSIS.  311 

kidney.  '  Blood-disks  usually  form  a  reddish-brown  de- 
posit. The  microscope  will  generally  exhibit  the  disks, 
unless  they  are  greatly  disintegrated,  when  we  must  be 
guided  by  the  quantity  of  albumen  and  other  tests. 
Blood  in  urine  may  proceed  from  some  general  disease  af- 
fecting the  bloodvessels  generally,  or  from  some  poisonous 
agent  acting  on  the  kidneys,  as  cantharides,  turpentine, 
creasote,  and  alcohol,  or  from  some  local  affection  of  the 
urinary  organs  and  passages.  Of  course  the  general  symp- 
toms of  the  patient  must  be  considered,  but  sometimes 
the  kind  of  epithelium  present  may  be  a  guide  to  the 
source  of  the  haemorrhage. 

SPERMATOZOA. 

Spermatozoa,  resembling  tadpoles  with  elongated  tails, 
are  not  uncommon  in  perfect  health,  but  nervous  patients 
are  often  deluded  by  quacks  on  account  of  them.  Of 
course,  when  present  habitually  and  in  large  numbers 
they  may  afford  evidence  of  spermatorrhoea. 


Bacteria  and  vibriones  often  appear  in  alkaline  and 
decaying  urine.  The  sugar  fungus  (Torula),  or  yeast  plant, 
is  developed  when  there  are  even  minute  traces  of  sugar. 
Other  fungi  with  branching  growths  are  also  frequent. 
Some  of  these  may  resemble  tube-casts.  Spores  of  globular 
shape  may  be  mistaken  for  blood-corpuscles.  Sarcime,  or 
minute  cubic  organisms,  dividing  into  groups  of  four  and 
its  multiples,  are  sometimes  found  in  the  urine  of  dyspep- 
sia. 

TUBE-CASTS. 

In  many  cases  of  congestion  and  inflammation  a  coagu- 
lable  material  is  effused  into  the  tubes  of  the  kidney, 
forming  a  cast  or  mould  of  the  tube.  This  may  be  ejected, 
bringing  with  it  pus,  blood,  epithelium,  or  other  material 


312  THE    MICROSCOPIST. 

with  which  it  is  associated.  In  Bright 's  disease  these 
casts,  in  addition  to  albuminous  urine,  assume  consider- 
able clinical  importance.  In  the  acute  form  of  the  disease 
the  cylinders  or  casts  are  fibrinous,  with  blood,  mucus, 
or  pus  cells,  and  epithelium.  Towards  the  close  the  casts 
become  homogeneous  or  hyaline.  In  chronic  desquama- 
tive  nephritis  the  cylinders  are  without  blood,  arid  to- 
wards the  end  waxy  or  fatty,  often  containing  many  oil- 
globules  (Plate  XXVI,  Fig.  241).  The  specimen  of  urine 
examined  for  casts  should  have  settled  for  several  hours,  and 
the  drop  of  sediment  examined  should  be  carefully  focussed 
and  illuminated.  The  casts  are  of  various  sizes,  those  of 
very  large  diameter  indicating  dilation  of  the  renal  tubules. 
In  bloody  or  purulent  urine  tube-casts  point  out  a  renal 
element  in  the  case.  They  do  not  always  indicate  Bright's 
disease,  as  they  may  be  associated  with  the  irritation  of 
a  calculus,  and  are  sometimes  found  in  jaundice  without 
serious  renal  trouble  or  albuminuria. 

CRYSTALLINE    AND    AMORPHOUS   DEPOSITS. 

Uric  Add. — Crystals  of  uric  acid  may  often  be  recog- 
nized as  a  red  sand,  lying  at  the  bottom  or  on  the  sides 
of  the  vessel,  or  entangled  in  mucus.  They  may  be  yel- 
low, red,  or  brown,  from  coloration  by  urinary  pigment. 
Their  microscopic  forms  are  various,  but  are  usually  some 
modification  of  the  rhomb.  Thus  they  may  be  rhomboid 
tablets  with  obtuse  angles,  or  the  shape  of  a  whetstone 
(Plate  XXVI,  Fig.  242).  When  slowly  precipitated,  uric 
acid  may  form  druses  of  four-sided  prisms  (Plate  XXVI, 
Fig.  243).  When  precipitated  from  fresh  urine  by  the 
addition  of  muriatic  acid,  the  crystals  are  large  and  often 
of  various  shapes.  They  may  be  tested  by  dissolving  in 
potassa  and  reprecipitating  by  muriatic  acid,  when  they 
assume  the  shape  of  Fig.  244,  Plate  XXVI.  Crystals  of 
uric  acid  may  occur  as  a  film  as  well  as  a  deposit.  They 
originate  from  tissue-waste,  excess  of  nitrogenous  food, 


THE    MICROSCOPE    IN    DIAGNOSIS.  313 

defective  assimilation,  congestion  of  the  kidney,  or  chronic 
disease  of  the  respiratory  organs. 

Unties  or  lithates  are  salts  of  uric  acid  combined  with 
soda,  potash,  or  ammonia,  the  exact  composition  being 
difficult  to  determine.  Such  sediments  are  very  common. 
They  are  generally  amorphous,  but  sometimes  crystalline 
(Plate  XXVI,  Fig.  245).  The  urate  of  soda  presents  the 
form  of  globules  with  projecting  spiculse.  The  color  is 
various,  from  a  light  pink  to  brickdust  color.  It  is  de- 
posited in  all  concentrated  urine,  and  is  often  a  "critical 
discharge  "  in  fevers,  etc.  It  is  found  in  gouty  concretions, 
and  dissolves  with  heat  and  acids. 

Phosphates  appear  in  two  forms,  crystalline  and  amor- 
phous. The  crystalline  are  the  crystallized  phosphate  of 
lime,  and  the  ammonio-magnesian  (or  "  triple")  phosphate. 
The  latter  is  most  common,  and  may  appear  in  any  de- 
composing urine.  It  may  be  precipitated  from  fresh  urine 
in  stellate  crystals  (Plate  XXVII,  Fig.  246)  by  adding 
ammonia.  More  slowly  deposited  from  alkaline  urine,  or 
in  disease,  the  crystals  are  prismatic,  generally  triangular, 
with  truncated  ends.  Sometimes  the  truncated  ends  are 
bevelled,  and  the  various  lengths  of  the  prisms  give  rise 
to  a  variety  of  forms  (Plate  XXVII,  Fig.  247). 

Triple  phosphates  are  generally  thought  to  proceed 
from  disintegrated  albuminous,  and  chiefly  nervous  mat- 
ter, but  their  clinica  limportance  is  riot  fully  settled. 
They  are  found  in  cases  of  nervous  depression,  various 
forms  of  dyspepsia,  shock  of  the  spinal  cord,  irritation  of 
the  bladder,  etc. 

In  highly  alkaline  urine  the  triple  phosphates  are  often 
accompanied  with  pus  and  phosphate  of  lime.  The  latter 
occurs  as  minute  granules  or  dumb-bells,  or  in  groups  of 
crystals  (Plate  XXVII,  Fig.  248).  They  are  dissolved  by 
acetic  acid,  which  distinguishes  them  from  uric  acid. 

Oxalate  of  lime  is  deposited  in  small  octohedra,  gener- 
ally appearing  under  the  microscope  as  minute  squares 
with  crossed  lines  proceeding  from  the  angles,  the  upper 


314  THE    MICROSCOPIST. 

angle  being  next  the  eye  (Plate  XXVII,  Fig.  249). 
Dumb-bell  forms  and  circular 'or  oval  crystalline  masses 
are  sometimes  seen. 

Oxalate  of  lime  is  found  as  a  urinary  deposit  in  various 
conditions,  as  in  pulmonary  and  dyspeptic  affections.  It 
is  usually  associated  with  hypochondriasis,  and  in  cases 
of  overfatigue,  particularly  from  mental  work,  it  is  com- 
mon. The  train  of  nervous  and  dyspeptic  symptoms  with 
which  it  is  associated  have  been  supposed  to  indicate  an 
"oxalic  acid  diathesis,"  and  have  been  named  "oxaluria." 
Its  association  with  calculi  renders  it  interesting  to  the 
surgeon. 

Chloride  of  sodium  never  crystallizes  from  fluid  urine. 
On  evaporation  it  occurs  in  stellar  form  or  in  cubes  (Plate 
XXVII,  Fig.  250).  The  presence  of  urea  sometimes  dis- 
poses it  to  assume  the  form  of  a  regular  octahedron.  The 
amount  of  this  excretion  in  typhoid  fever  and  in  inflam- 
mations of  the  respiratory  organs  is  greatly  diminished. 
It  is  absent  in  commencing  hepatization  of  the  lung,  but 
returns  on  resolution  of  the  inflammation  (see  Chlorides, 
page  302). 

Cystin  crystallizes  in  characteristic  six-sided  plates 
(Plate  XXVII,  Fig.  251).  It  contains  twenty-six  per 
cent,  of  sulphur,  and  is  considered  a  product  of  decompo- 
sition. It  is  often  associated  with  calculus.  Some  regard 
it  as  indicating  a  strurnous  and  ill-nourished  system. 

Carbonate  of  lime  occurs  rarely  in  human  urine,  but  is 
common  in  that  of  the  horse.  Its  form  is  that  of  a 
spherule  made  up  of  acicular  crystals.  It  effervesces  in 
acetic  acid. 

Tyrosin,  in  sheaflike  or  globular  masses,  sometimes 
occurs  in  typhus  and  in  atrophy  of  the  liver. 

III.    PUS    AND   MUCUS   IN   DIAGNOSIS. 

"We  have  already  considered  the  bioplasts  of  pus  and 
mucus  as  identical  in  character  with  other  leucocytes,  as 


PLATE    XXVII. 


FIG.  246. 


Ammonio-phosphjvte  of  Magnesia. 


Ammonio-phosphate  of  Magnesia. 


FIG.  248. 


&^=>  w^x — 

*     ^-fe     *f7 

.         «U$^    jr^A 

Phosphate  of  Lime. 


FIG.  250. 


%s£ 

1 


FIG.  249. 


J? 


CO  c? 


Chloride  of  Sodium. 


Oxalate  of  Lime. 


FIG.  251. 


I  oO 

/^\         rsjCfcl 

Cystine. 


FIG.  252. 


Salivary  corpuscles,  epithelial  scales  and  granules. 


THE    MICROSCOPE    IN    DIAGNOSIS.  315 

the  white  blood-cells  (see  pages  189  and  309).  They 
are  easity  seen  by  the  microscope  in  a  drop  of  purulent 
matter  placed  on  a  slide  and  covered  by  thin  glass.  Pus- 
corpuscles  shrink  in  size  on  being  placed  in  liquid  of 
greater  specific  gravity  than  serum,  and  are  destroyed  by 
the  action  of  caustic  alkalies  so  as  to  be  changed  into  a 
tenacious  glairy  mass.  Dilute  acetic  acid  causes  them  to 
swell  and  become  transparent,  exhibiting  from  one  to  four 
nuclei.  Bacteria  and  their  germs  (microzyrnes)  are  often 
seen  with  pus,  and  indicate  commencing  decomposition. 

According  to  Dr.  Beale,  the  figures  and  descriptions 
generally  given  of  pus  represent  dead,  not  living  pus.  He 
recommends  a  little  pus  to  be  taken  from  suppurating 
skin  or  mucous  membrane  and  examined  at  once,  in  order 
to  see  the  projections  from  the  bioplasts,  by  the  detach- 
ment of  which  they  multiply.  He  considers  the  "  mucous 
corpuscle"  to  be  nothing  more  than  an  imperfect  epithe- 
lial cell  surrounded  by  the  viscid  mucus  formed  by  it. 
This  may  grow  rapidly,  and  the  resulting  particles  become 
true  pus-corpuscles. 

Richardson  regards  the  difference  between  pus  and 
mucus  to  be  that  "the  liquor  muci  is  a  secretion,  which, 
having  been  acted  upon  by  the  germinal  matter  of  the 
epithelial  cells  covering  the  basement  mucous  membrane, 
is  not  albuminous,  while  the  liquor  puris  is  an  exudation, 
which  contains  albumen,  that  may  be  recognized  by  ap- 
propriate tests." 

IV.    EXAMINATION   OF   MILK. 

Examination  of  human  milk  may  sometimes  aid  in 
diagnosis,  as  in  contusions  of  the  breast,  incipient  mastitis, 
and  in  the  diarrhoea  and  innutrition  of  infants.  The  origin 
of  milk  may  be  elucidated  by  the  remarks  on  lactification 
on  page  233. 

A  thin  stratum  of  milk  should  be  examined  with  a 
power  of  from  200  to  400  diameters,  and  an  estimate 


316  THE    MICROSCOPIST. 

made  of  the  milk-globules,  as  in  the  ease  of  the  blood- 
corpuscles  (page  296);  or  the  sample  may  be  compared 
with  a  specimen  known  to  be  healthy. 

Impoverished  milk  is  known  by  the  small  number  and 
size  of  the  globules.  Colostrum  or  "  exudation  "  corpus- 
cles are  numerous  shortly  after  childbirth.  In  engorge- 
ment of  the  breast  the  globules  aggregate  in  masses,  and 
sometimes  from  inflammation,  blows,  etc.,  blood  and  pus 
may  be  found.  Starchy  adulteration  may  be  detected  by 
the  addition  of  iodine.  Richardson  speaks  of  fibrinous 
casts  of  the  lacteal  ducts  occurring  after  puerperal  masti- 
tis, and  Beale  of  minute  particles  of  contagious  bioplasm 
in  the  milk  of  a  cow  suffering  from  cattle-plague,  and 
considers  it  possible  that  typhoid  fever,  etc.,  may  be  thus 
propagated. 

Y.    SALIVA    AND   SPUTUM. 

Besides  the  epithelium  of  the  mouth,  saliva  holds  in 
suspension  certain  oval  or  spherical  bodies,  probably  de- 
rived from  the  glandular  follicles,  called  "  salivary  cor- 
puscles "  (page  189). 

Dr.  Richardson  considers  them  identical  with  leuco- 
cytes. Beale  supposes  them  to  be  concerned  with  the  con- 
version of  starch  into  sugar,  which  occurs  from  the  action 
of  the  saliva.  The  peculiar  dancing  movement  of  the 
granules  of  these  corpuscles  needs  a  y^th  of  an  inch  object- 
glass,  or  one  even  higher,  to  see  them  well. 

In  examining  sputum  a  small  piece  should  be  placed  on 
a  slide  and  teased  out  with  needles,  if  necessary,  in  glyc- 
erin and  water,  or  some  indifferent  fluid.  We  may  ex- 
pect to  find  mucus  entangling  air-bubbles  and  pavement 
epithelium  from  the  mouth  (Plate  XXVII,  Fig.  252).  The 
observer  should,  however,  be  familiar  with  the  appear- 
ance of  fragments  of  food,  starch,  epithelium  from  the 
various  parts  of  the  air-passages,  fungi,  etc. 

In  catarrhal   affections   ciliated   epithelium   from   the 


THE    MICROSCOPE    IN    DIAGNOSIS.  317 

nasal  or  respiratory  passages  may  be  seen,  and  perhaps 
molecules  of  fat,  pus-globules,  blood,  and  "  inflammatory 
corpuscles."  In  phthisis  the  decaying  lung  may  be  early 
detected  by  the  fibres  of  elastic  tissue  from  the  walls  of  the 
pulmonary  vesicles.  The  sputa  should  be  first  liquefied 
by  boiling  a  little  while  in  an  equal  bulk  of  caustic  soda, 
then  allowed  to  settle  in  a  conical  glass,  when  a  small 
quantity  may  be  removed  to  a  glass  slide,  covered  with 
thin  glass,  and  placed  under  the  microscope. 

The  occurrence  of  fungi  in  sputum  is  to  be  expected 
whenever  there  is  decay.  The  Leptothrix  buccalis,  one 
form  of  penicillium,  is  common  on  old  epithelial  scales  of 
the  mouth,  and  in  the  latter  stages  of  phthisis  the  sputa 
will  often  show  fungi  in  various  forms  of  development. 

In  catarrhal  pneumonia  we  may  find  fibrinous  casts  of 
the  alveoli  of  the  lungs  and  epithelial  elements,  chloride 
of  sodium,  etc.  Hydatids  are  sometimes  expectorated  in 
sputum,  the  appearance  of  the  booklets  of  the  echinococci 
being  quite  characteristic.  Scales  of  cholesterin  and 
blood-crystals  may  also  occur,  as  well  as  calcareous  con- 
cretions and  dark  melanotic  masses. 

Richardson  states  that  associated  matters  may  indicate 
the  source  of  blood  in  sputum.  Thus  associated  salivary 
corpuscles  might  show  haemorrhage  within  the  mouth, 
amoeboid  leucocytes,  haemorrhage  in  the  fauces  or  trachea, 
starch -granules  and  particles  of  food,  hsematemesis,  and 
coagulated  casts,  pulmonary  hsemorrhage. 

VI.    VOMITED    MATTERS. 

Microscopic  examination  of  vomited  matters  reveals 
muscular  fibres,  starch-granules,  oil-globules,  and  shreds 
of  vegetable  tissue,  according  to  the  diet  of  the  patient. 
Crystals  of  margarin,  etc.,  are  often  seen.  Blood,  pus, 
etc.,  may  be  recognized  if  their  structure  be  not  destroyed 
by  the  digestive  fluids. 

Isolated  specimens  should  be  picked  out  with  forceps 


318  THE    MICROSCOPIST. 

and  scissors,  or  the  vomit  should  stand  some  time  in  a 
conical  glass  and  a  little  of  the  deposit  removed  with  a 
pipette. 

Torula  and  other  forms  of  fungi  are  often  seen  in  vom- 
ited matters.  The  vomit  containing  the  sarcina  ventrlculi 
generally  ferments  like  yeast. 

The  color  of  the  "  coffee  grounds  vomit"  is  due  to  dark- 
brown  pigment,  probably  the  altered  coloring  matter  of 
blood. 

Some  specimens  of  cholera  vomit  showed  numerous 
flocculi,  consisting  of  epithelium.  The  clear  fluid  of  py- 
rosis contains  only  a  little  epithelium  and  a  few  small  oil- 
globules.  The  green  vomit  depending  on  bile  contains 
cylindrical  epithelium  from  the  gall-ducts,  scaly  epithe- 
lium, flakes  and  masses  of  biliary  coloring  matter,  and  fat- 
globules. 

Dr.  Beale  records  a  case  of  the  detachment  of  flakes  of 
stomach  epithelium  in  a  case  of  scarlet  fever. 

Biliary  matters,  as  cholesterin,  etc.,  and  even  small  gall- 
stones, have  been  rejected  by  vomiting. 

VII.    INTESTINAL    DISCHARGES, 

Microscopists  are  not  unfrequently  called  upon  to  ex- 
amine dubious  matters  passed  from  the  bowels.  Dr.  Ben- 
net  describes  one  case  of  yellowish  pulpy  masses  passed 
with  the  stools  as  consisting  of  undigested  potato  skins, 
and  another  made  up  of  a  network  of  confervoid  growths 
developed  in  the  intestinal  canal.  In  one  case,  seen  by 
the  author,  tormina,  etc.,  were  produced  by  skins  of  grapes ; 
another  case  exhibited  the  skin  or  testa  of  a  large  seed, 
as  the  tamarind.  These  instances  show  the  necessity  of 
the  observer  being  familiar  with  various  botanical  and 
histological  appearances. 

Blood-globules  in  feeces  retain  their  natural  appearance 
in  inverse  proportion  to  the  distance  of  the  hsemorrhagic 
point  from  the  anus,  so  that  quite  fresh  blood  will  indicate 


THE    MICROSCOPE    IN    DIAGNOSIS.  319 

hsemorrhoids,  fistula,  etc.,  while  more  disintegrated  disks 
indicate  effusion  further  up  the  intestinal  tube. 

Mucous  casts  or  coagula  of  albuminous  matters  are  not 
very  uncommon,  either  in  flakes  or  tubular  casts.  The 
mucus  entangles  epithelial  cells,  usually  from  the  large 
intestine.  In  typhoid  fever  crystals  of  triple  phosphates, 
altered  blood,  bacteria,  and  various  fungi  may  be  found 
in  the  faeces,  and  the  stools  of  cholera  patients  contain 
large  quantities  of  cylindrical  epithelium,  so  that  the 
white  flocculi  are  almost  entirely  composed  of  it. 

Elastic  fibres,  exhibiting  transverse  striae  like  those  of 
the  ligamentum  nuchse  of  the  giraffe,  are  sometimes  found 
arising,  in  all  probability,  from  incipient  decomposition 
of  ingesta. 

Larvae  of  insects  may  sometimes  be  passed  alive  from 
the  bowels,  as  well  as  be  ejected  from  the  stomach.  The 
various  forms  of  intestinal  worms  in  their  various  stages 
of  development  may  also  be  met  with.  In  some  instances 
the  microscope  is  needed  to  distinguish  between  suspected 
worms,  or  portions  of  worms,  and  accidental  products. 
Fatty  matter  in  the  stools,  sometimes  semisolid,  is  usually 
attributed  to  derangement  of  the  pancreas. 

VIII.    VAGINAL   DISCHARGES. 

The  diagnostic  value  of  discharges  from  the  vagina, 
either  uterine  or  vaginal  in  their  origin,  has  been  yet  but 
little  studied,  and  presents  a  field  of  special  interest  in 
gynaecology.  The  discharge  should  be  examined  while 
fresh  and  without  the  addition  of  water  or  other  fluids  if 
possible.  Should  fluid  menstrua  be  really  necessary,  in- 
different fluids  only  should  be  used. 

The  menstrual  discharge  will  be  likely  to  contain  young 
and  old  epithelial  scales  and  blood-globules.  In  dysrnenor- 
rhoea  considerable  patches  of  the  epithelial  membrane 
desquamate,  and  even  entire  casts  of  the  uterus  or  vagina 


320  THE    MICROSCOPIST. 

have  been  separated.  The  diagnosis  between  dysmenor- 
rhoea  and  abortion  may  be  determined  by  a  microscopic 
examination  of  such  fragments,  since  the  villi  of  the 
chorion  can  be  thus  recognized  if  present. 

In  leucorrhoea  old  epithelial  cells,  loaded  with  fat,  will 
be  seen,  with  imperfectly  formed  epithelium  and  pus 
globules.  Beale  states  that  the  development  of  pus-cor- 
puscles from  the  bioplasts  of  epithelium  may  be  success- 
fully studied  in  leucorrhceal  discharges.  Sometimes  blood- 
globules  will  be  seen  altered  by  exosmosis,  etc. 

The  white  gelatinous  discharge  from  the  os  uteri,  often 
seen  in  uterine  catarrh,  consists  of  mucus  with  epithelial 
elements. 

Fibrous,  epithelial,  and  cancerous  tumors  or  ulcers  may 
sometimes  be  recognized  by  their  microscopic  elements, 
yet  it  must  be  remembered  that  altered  epithelium  may 
be  readily  mistaken  for  the  elements  of  cancer,  etc. 

The  Trichomonas  vaginalis  (Donne)  is  common  in  the 
yellow  acrid  mucus  of  vaginal  blennorrhoea.  It  is  a  round- 
ish ciliated  animalcule,  and  may  be  distinguished  from 
ciliated  epithelium  by  the  elongation  of  the  anterior  end, 
which  is  sometimes  drawn  out  into  a  long  filament  or 
flagellum. 

The  epithelium  from  the  Fallopian  tubes  and  uterus  is 
columnar  and  ciliated,  while  that  of  the  vagina  is  squa- 
mous,  with  large  cells. 

Accidental  products  may  also  be  discharged  from  the 
vagina,  as  well  as  from  other  cavities.  In  one  case  I  found 
a  number  of  living  Crustacea  (Gammara-pulex},  which  oc- 
casioned great  pruritus,  but  were  dislodged  by  injections 
of  sweet  oil. 

Dr.  Sims  has  shown  how  the  microscope  may  aid  in  the 
cure  of  sterility,  since  the  uterine  cervical  mucus  needs  to 
be  slightly  alkaline.  If  habitually  acid  it  destroys  the 
spermatozoa. 


THE    MICROSCOPE    IN    ETIOLOGY.  321 


CHAPTER   XV. 

THE    MICROSCOPE    IN   ETIOLOGY. 

THE  study  of  aetiology,  or  the  knowledge  of  the  causes 
of  disease,  although  so  important  a  branch  of  practical 
medicine,  needs  the  careful  and  united  efforts  of  many 
observers  to  be  classified  and  recorded  before  approaching 
perfection.  Here,  also,  the  microscope  will  be  found  an 
important  aid.  The  numerous  external  causes  of  disease, 
such  as  physical  or  organic  impurities  in  the  atmosphere, 
soil,  water,  and  food,  vegetable  or  animal  parasites,  and 
"disease  germs,"  with  their  relation  to  epidemic  or  en- 
demic disorders,  all  require  skilful  use  of  the  microscope. 

I.    EXAMINATION   OF    THE    AIR. 

The  pressure,  temperature,  moisture,  and  electricity  of 
the  air,  all  of  which  are  important  in  considering  causes 
of  disease,  require  other  modes  of  investigation,  but  the 
microscope  maybe  reasonably  expected  to  aid  in  inquiries 
concerning  mechanical,  chemical,  o'r  organic  impurities. 

Many  methods  have  been  proposed  for  collecting  mat- 
ters suspended  in  the  atmosphere.  A  shallow  dish  con- 
taining distilled  water,  or  a  clean  glass  vessel  containing 
ice,  so  as  to  condense  the  atmospheric  moisture  with  its 
impurities  on  the  outside,  and  allow7  it  to  trickle  into  a 
conical  receiver,  have  been  used.  Glass  plates  moistened 
with  glycerin  and  exposed  to  the  air  are  still  better.  The 
aeroscope  of  Dr.  Maddox  is  a  funnel-shaped  tube  turned 
to  the  wind  by  a  vane.  The  narrow  end  of  the  tube  is 
opposite  a  slide  moistened  with  glycerin. 

Many  absurd  "  discoveries  "  have  been  paraded  respect- 
ing matters  in  air  and  water,  yet  careful  observation  will 

21 


322  THE    MICROSCOPIST. 

reveal  valuable  facts.  Solid  fragments  of  carbon  or  silex, 
etc..  starch  grains,  filaments  of  cotton,  flax,  wool,  silk, 
etc.,  spores  of  fungi,  animal  and  vegetable  debris,  etc.,  all 
require  considerable  familiarity  with  microscopic  objects 
in  general,  without  which  no  one  should  undertake  such 
investigations. 

Minute  living  particles  of  bioplasm,  either  ordinary  pus 
or  what  Dr.  Beale  calls  "disease  germs,"  should  be  dili- 
gently sought  for  under  high  objectives. 

Pollen-grains  are  often  found  in  the  air.  In  Schuylkill 
County,  Pa.,  in  the  summer  of  1858,  after  a  rain-shower, 
a  yellow  scum  of  pollen  covered  all  the  pools,  and  was 
traced  over  a  tract  of  fifty  by  twelve  miles.  Showers  of 
"flesh"  or  "blood"  have  been  described  in  newspapers, 
which  were  probably  varieties  of  Nostoc  (page  151),  or  pig- 
ment bacteria  (page  326). 

The  subject  of  bacteria  germs  in  the  air  has  lately  ac- 
quired great  interest  from  the  success  of  the  antiseptic 
method  now  generally  pursued  in  large  surgical  opera- 
tions, and  first  introduced  by  Mr.  Lister.  This  will  be 
considered  under  the  head  of  disease  germs. 

The  examination  of  the  breath  of  men  or  animals  may 
be  made  by  means  of  glycerin  on  glass  slides,  or  by  breath- 
ing through  a  glass  tube  containing  cotton-wool,  which 
may  afterwards  be  washed  with  dilute  glycerin.  Epithe- 
lial cells,  oil-globules,  fragments  of  food,  soot,  fungi,  etc., 
may  thus  be  detected,  or  the  expired  air  may  be  tested 
for  ammonia  with  hydrochloric  acid. 

II.    EXAMINATION   OF   SOIL    AND   WATER. 

The  soil  may  be  examined  both  chemically  and  micro- 
scopically according  to  the  methods  given  on  former  pages 
of  this  work.  The  importance  of  such  examination  will 
be  plain  in  many  cases  of  local  diseases.  It  is  stated  that 
the  mortality  caused  by  murderous  epidemics  in  England 


THE    MICROSCOPE    IN    AETIOLOGY.  323 

has  been  greatly  diminished  since  the  systematic  building 
of  sewers  and  the  prohibition  of  pitlike  privies  in  towns. 

Dr.  Salisbury's  observations  on  the  growth  of  certain 
fungi  as  the  cause  of  malarious  fevers,  although  requiring 
further  confirmation,  suggest  a  very  pertinent  line  of  in- 
quiry. 

Drinking-water  may  be  vitiated  by  organic  matter  and 
its  chemical  products,  as  ammonia,  chlorine,  and  the  ni- 
trates. Wagner  states  that  to  be  drinkable  it  must  not 
contain  in  100,OuO  parts  more  than  0.4  parts  of  nitric  acid, 
0.8  parts  of  chlorine,  and  5  parts  of  organic  matter.  Boil- 
ing does  not  improve  such  water.  It  is  generally  made 
impure  by  sewage,  and  produces  gastric  and  intestinal 
diseases,  arid  perhaps  typhoid  fever. 

III.    EXAMINATION   OF   FOOD,    ETC. 

The  adulteration  of  food  has  long  been  a  question  of 
interest,  and  has  been  investigated  by  a  host  of  observers. 
Dr.  Hassall's  voluminous  researches,  however,  leave  little 
to  be  desired.  He  states  that  "in  nearly  all  articles, 
whether  food,  drink,  or  drugs,  my  opinion  is  that  adul- 
teration prevails.  And  many  of  the  substances  emplo37ed 
in  the  adulterating  process  were  not  only  injurious  to 
health,  but  even  poisonous."  Dr.  Hassall's  work,  Food 
and  its  Adulterations,  should  be  used  by  all  who  inquire 
into  this  subject,  which  is  too  voluminous  to  be  considered 
here  in  detail.  Familiarity,  however,  with  the  subjects 
already  discussed  in  this  work  will  qualify  the  observer 
for  such  examinations.  Wheat-flour  may  be  examined 
by  adding  a  little  water,  and  then  a  few  drops  of  a  solu- 
tion of  potash  (one  part  liquor  potassse  to  three  of  water). 
Granules  of  potato-starch  swell  by  this  means  to  three  or 
four  times  their  natural  size,  while  those  of  wheat-starch 
are  scarcely  affected  by  it.  Comparisons  of  different  kinds 
of  starch  under  the  microscope  will  guide  in  many  other 


324  THE    MICROSCOPIST. 

investigations.  Adulteration  of  flour  with  alum,  etc., 
may  be  detected  by  dissolving  the  alum  and  recrystalliz- 
ing  under  the  microscope. 

Coffee  is  adulterated  with  chiccory,  wheat,  corn,  etc. ; 
tea  with  foreign  leaves,  Prussian  blue,  clay,  etc. ;  choco- 
late with  brickdust,  peroxide  of  iron,  animal  fat,  etc. 

IV.    PARASITES. 

Parasites  are  animal  or  vegetable  organisms  which  live 
temporarily  or  permanently  upon  or  within  another  or- 
ganism for  their  nourishment  and  development.  Casual 
visitors  for  the  sake  of  moisture,  warmth,  or  products  of 
decomposition  (as  many  fungi  and  infusoria)  are  called 
pseudo-parasites.  Van  Beneden  distinguishes  between 
messmates  which  are  nourished  in  common,  mutualists 
which  live  on  and  serve  each  other,  and  parasites  which 
live  at  others'  expense. 

In  this  department  of  science  the  student  will  do  well 
to  consult  Cobbold's  magnificent  work  on  Entozoa,  and 
two  of  the  recently  published  international  scientific  series 
of  books,  viz.,  Fungi^y  Cooke  and  Berkely,  and  Animal 
Messmates  and  Parasites,  by  Van  Beneden. 

The  plan  of  Wagner,  in  his  Manual  of  General  Pathol- 
ogy',  is  followed  in  the  present  outline,  so  far  as  classifica- 
tion is  concerned. 

I.  VEGETABLE  PARASITES  OR  EPIPHYTES. 
I.  FUNGI. 

The  general  character  and  development  of  fungi  have 
been  described  at  page  136.  The  subject  of  polymor- 
phism also  has  been  referred  to  as  indicating  the  uncer- 
tainty of  distinguishing  genera  and  species.  Cooke  re- 
minds us,  however,  that  polymorphism  can  only  be  based 
upon  actual  organic  continuity,  the  observance  of  which 
in  such  minute,  organisms  is  necessarily  difficult. 


THE    MICROSCOPE    IN    ETIOLOGY.  325 


A.    DUST    OR   GERM   FUNGI,   CONIO    OR   GYMNOMYCETES. 

1.  Mycoderma  (Cryptococcus). — The  beer-yeast  (Micro- 
coccus,  or  Torula  cerevisice)  consists  of  round  or  oval  color- 
less cells  containing  one,  and  sometimes  two  bright  nuclei 
resembling  oil-globules.  New  cells  arise  from  these  by 
budding.  No  proper  filament  or  mycelium  is  formed. 

The  milk-yeast  (Oidium  lactis]  can  grow  fungus-like  if 
submerged,  while  on  the  surface  is  a  mycelium  of  articu- 
lated filaments  from  which  shoots  grow  up,  wrhose  cells 
separate  easily. 

Schwann,  Pasteur,  etc.,  consider  the  yeast-fungi  as  or- 
ganisms produced  by  specific  germs,  while  others  regard 
them  as  spores,  which  in  the  atmosphere  fructify  in  other 
forms. 

B.    FILAMENTOUS   FUNGI,   HYPHOMYCETES. 

The  mycelia  of  these  are  lengthened  tubular  cells,  often 
branching.  The  spores  originate  within  or  at  the  end  of 
filaments.  Here  belong  the  fungus  of  the  muscardine  of 
the  silkworm  (Botrytis  bassiana),  the  potato  disease  (Fusi- 
porium  solani),  the  grape  disease  (Oidium  tuckerii),  mould, 
and  the  fungi  occurring  in  diseases  of  skin  and  mucous 
membranes. 

1.  Penicillium  glaucum,  common  mould  or  pencil  mould, 
forms  most  of  the  mould  occurring  upon  vegetable  de- 
composing  substances.     The   fruit-bearers   rise    from    a 
branched  colorless  mycelium.     The  points  are  tufted  and 
bear  spherical  conidia. 

2.  Aspergillus  glaucu?,  or  green  mould,  is  often  found 
with  the  foregoing.     The  fruit-filaments  expand  into  club- 
shaped  basidia.     The  spores  are  greenish. 

3.  Mucor  mucedo  and  Mucor  racemosus  are  found  on 
excrement   arid  old   articles  of  food.     The  bladder-like 
swollen  fruit-hyphen  (columella)  rises  from  a  branched 


326  THE    MICROSCOPIST. 

filamentous  mycelium,  which  becomes  septate  with  age. 
The  spores  are  set  free  by  breaking  of  the  wall  of  the 
sporangium. 


C.  CLEFT  FUNGI,  SCHIZOMYCETES  (bacterium,  micrococcus). 

The  term  schizomycetes  is  given  from  the  great  fra- 
gility of  the  formation.  They  are  cells  without  chloro- 
phyll, of  various  forms,  which  increase  exclusively  by 
transverse  division.  The  cell-membrane  is  not  destroyed 
by  potassa,  nor  by  acids,  and  resists  decomposition  for  a 
long  time. 

1st  Group.  Spherobacteria. — Globular  bacteria  (Pas- 
teur's Monas  or  Mycoderma.  Ehrenberg's  Monas  corpus- 
culum  and  prodigiosa.  Hallier's  Micrococcus). 

Spherical  or  oval  cells,  without  granular  contents,  pos- 
sessing a  double  contour,  and  becoming  moniliform  by 
division.  Often  difficult  to  distinguish  from  granular 
detritus. 

1st  Genus.  Micrococcus  (Cohn). — Bells  colorless  or  nearly 
so,  very  small,  united  into  short  moniliform  filaments  of 
two  or  more  members  (mycrothrix,  torula-forms),  or  into 
many-celled  families,  balls,  or  colonies,  or  into  mucous 
masses  (zoogloa-forms,  mycoderma-forms).  No  movement. 

(1.)  Pigment  bacteria.  Appearing  in  colored  jellylike 
masses. 

a.  Coloring  matter,  insoluble,  red  and  yellow. 

1.  Micrococcus  Prodigiosus  (Palmella  prod.). — Cause  of 
the  seeming  blood-spots  which  sometimes  appear  during 
moisture  on  wafers,  bread,  potatoes,  etc. 

2.  M.  luteus. 

b.  Coloring  matter,  soluble.    M.  aurantiaceus,  chlorinus, 
etc. 

(2.)  Zymogenic  globular  bacteria. 

3.  Microccocus  Urea. — Ferment  of  urine. 


THE    MICROSCOPE    IN    AETIOLOGY.  327 

(3.)  Pathogenic  globular  bacteria.  "  Ferments  of  con- 
tagion." 

4.  M.  vaccines. 

5.  M.  diphthericus 

6.  M.  Septicus. — Some  deem  it  the  cause  of  pyaemia. 

7.  M.  Bombycis. — A  destructive  epidemic  among  silk- 
worms of  Southern  France,  but  different  from  muscardine 
and  gattine. 

2<f  Group.  Microbacteria. — Rodlike  bacteria,  resemble 
globular  bacteria  in  the  small  size  of  cells  and  their  tem- 
porary union  into  mucous  masses,  but  are  distinguished 
by  their  short  cylindrical  forms  and  spontaneous  move- 
ments. 

2d  Genus.  Bacterium. 

1.  Bacterium  Termo. — Cells   short,  cylindrical,  oblong. 
They  turn  on  their  axis  and  swim  forward,  then  return  a 
little  or  travel  in  curved  lines  as  if  trembling,  or  spring- 
ing forward  and  then  becoming  quiet. 

2.  B.  Lineola. — Cells  cylindrical,  broad,  straight,  with 
refractive  soft  contents,  and  fatlike  granules.     Single  or 
in  pairs. 

%d  Group.  Desmobacteria — Filamentous  B. — Filaments 
not  constricted  at  the  joints,  but  throughout  cylindrical 
(leptothrix  filaments).  May  form  swarms  but  not  zoogloa- 
form  masses. 

1st  Genus.  Bacillus. — Filaments  straight. 

1.  B.  Subtilis. — Butyric  acid  ferment. 

2.  B.  Anthracis. — Bacteridia  of  gangrene  of  the  spleen. 

3.  B.  Ulna. 

2d  Genus.  Vibrio. — Filaments  wavy,  thick,  with  single 
curve  ( V.  rugla),  or  thin,  with  many  curves  (  V.  serpens). 

4th  Group.  Spirobacteria. — Screw  bacteria.  Distin- 
guished from  vibrio  by  the  closer  regular  permanent  spiral 
of  the  filament. 

1st  Genus.  Spirochceta. 

1.  8.  Plicatilis. — In  tartar  from  the  teeth. 


328  THE    MICROSCOPIST. 

2d  Genus.  Spirillum. — Shorter  and  more  distant  spiral. 

5th  Group. 

1st  Genus.  Leptothrix. 

1  L.  Buccalis. — Long,  brittle,  slender  filaments,  divided 
by  partition-walls.  Occurs  on  products  of  decomposition 
within  the  mouth  ;  papillse  of  tongue,  tartar,  etc.  Also 
in  the  intestine,  vagina,  etc.  It  is  thought  by  some  to 
produce  caries  of  the  teeth. 

2d  Genus.  Sarcina. 

1.  S.  Ventriculi. — Four-fold  flat  cubical  cells,  generally 
with  nuclei.  Occurs  in  vomited  fluid,  urine,  etc. 

In  addition  to  the  above  (provisional)  arrangement, 
Wagner  classifies  vegetable  parasites  with  respect  to  their 
pathological  relations  as  follows : 


I.    MOULD   DISEASES. 

These  are  conditional  upon  the  above-mentioned  mould 
fungi.  They  occur  chiefly  upon  parts  affected  with  ne- 
crosis or  other  lesions,  particularly  ulcers  of  the  skin  and 
mucous  membranes.  On  free  surfaces  they  present  an 
appearance  resembling  mould.  Perhaps  in  this  connec- 
tion belongs  the  foot-fungus,  or  Mycetoma  Carterii,  which 
is  endemic  in  India. 

II.    FUNGI   OF    TRUE    PARASITIC   DISEASES   OF   THE   SKIN 
AND   MUCOUS   MEMBRANES. 

1.  Trico^hyton  Tonsurans. — This  consists  of  round  trans- 
parent spores,  or  spore-rows.  They  develop  in  the  roots 
of  the  hair  and  pass  into  the  shaft,  so  that  the  latter  is 
destroyed  and  breaks  off.  It  occurs  also  in  the  sheaths 
of  the  hair-roots  and  surrounding  epidermis,  seldom  in 
the  nails.  It  causes  several  diseases,  especially  of  the 
scalp  and  beard,  as  herpes  tonsurans,  porrigo  scutellate,  men- 


THE    MICROSCOPE    IN    AETIOLOGY.  329 

tagra  (sycosis],  eczema  marginatum,  etc.     It  is  thought  by 
some  to  proceed  from  aspergillus. 

In  examining  hair,  skin,  etc.,  for  fungi,  the  specimens 
should  be  soaked  in  liquor  potassae  long  enough  to  become 
transparent. 

2.  Achorion  Schonleinii — Favus  Fungus. — Mjcelia  com- 
posed of  small,  simple,  or  branching  tubes  divided  by  par- 
titions.     Spores   round  or  oval,   sometimes   grouped   in 
masses.     The  cause  of  tinea  favosa  of  the  scalp.  . 

3.  Mwrosporon  Audouinii. — Undulating  forked  filaments 
on  which  spores  are  directly  placed.     Found  round  the 
shaft  of  the  hair  after  its  exit  from  the  follicle,  so  thick 
that  the  hair  breaks  off  and  causes  baldness.     Porrigo  de- 
calvans. 

4.  Microsporon  Furfur. — Masses  of  large,  round,  mostly 
nucleated  spores,  and  long  or  branched  cells.     Sometimes 
with  numerous  broad  filaments.     Developed  in  the  horny 
layer  of  the  epidermis,  commonly  round  the  opening  of 
hair  follicles  of  the  breast  and  back,  producing  yellowish 
discoloration  and  branlike  scales,  with  itching, — Pityria- 
sis  versicolor. 

5.  Oidium    Albicans — Thrush   Fungus — Tubular   fila- 
ments, branching  stems,  and  minute  spores.     Ends  of  fila- 
ments lost  in  masses  of  spores,  with  a  large,  often  divided 
spore-cell.   Found  in  aphthae  of  the  mouth,  tongue,  throat, 
vagina,  etc. 

III.    FUNGI  AS   EXCITORS  OF    FERMENTATION  AND    PUTRE- 
FACTION  AND   CAUSES  OF    DISEASE. 

At  page  137  the  distinction  between  diseased  conditions 
which  invite  fungi  and  the  effects  produced  by  fungi 
themselves  was  stated.  '  That  fungi  are  the  cause  of  spe- 
cific fermentations  (acetic,  alcoholic,  lactic,  butyric,  etc.), 
is  rendered  very  probable  by  modern  researches,  especially 
those  of  Pasteur.  In  decay,  or  oxidation,  and  in  putre- 


330  THE    MICROSCOPIST. 

faction  of  organic  bodies,  fungi  are  important  agents. 
In  the  former  vibrios  are  found,  and  in  the  latter  monads 
and  bacteria.  Decay  is  arrested  if  access  of  fungus  germs 
is  prevented.  Putrefaction  is  as  dependent  on  bacteria  as 
the  fermentation  of  non-nitrogenous  bodies  upon  yeast- 
fungi. 

Many  acute  infectious  diseases  are  considered  to  pro- 
ceed from  fungi,  although  the  reasons  for  such  an  opinion 
are  chiefly  theoretical,  arising  from  the  presence  of  fungi 
in  those  diseases.  Such  are  diphtheria,  pyaemia,  puer- 
peral fever,  small-pox,  etc.  Many  experiments  have  been 
made,  by  inoculation,  etc.,  but  thus  far  with  little  results. 
Observers  differ  greatly  concerning  the  same  disease,  the 
specific  fungus  of  one  being  disavowed  by  another.  Still, 
much  light  may  be  expected  respecting  aetiology  from  ob- 
servations of  this  kind. 

II.  ANIMAL  PARASITES. 

These  inhabit  either  the  external  surface  (epizoa)  or 
internal  organs  (entozoa). 

I.  PROTOZOA. 

GREGARINIDJE. — See  page  180.  Gregarinidce  are  para- 
sitic animals,  generally  regarded  as  the  lowest  of  the  pro- 
tozoa, although  this  opinion  is  doubtful.  They  usually 
consist  of  a  single  cell,  with  an  illy-defined  membrane 
filled  with  granular  and  fatty  sarcode,  with  nucleus  and 
nucleolus.  They  are  developed  much  like  protophytes, 
page  140.  The  gregarina  becomes  motionless,  globular, 
and  encysted.  The  nucleus  then  disappears  and  the  sar- 
code breaks  up  into  little  masses  which  become  pointed 
at  each  end  (pseudo-navicellse).  These  masses  escape  as 
amoeba,  page  121,  and  develop  new  gregarince. 

Globular  psorospermice,  as  they  are  called,  have  been 


THE    MICROSCOPE    IN    ETIOLOGY.  331 

found  in  the  liver  and  intestines  of  rabbits  and  of  man, 
and  are  regarded  as  the  resting  stage  of  yregarince. 

INFUSORIA. — Family,  Heterotricha. — Body  covered  with 
cilia,  often  in  longitudinal  rows.  Stronger  cilia  about 
the  mouth. 

Balantidium  Boli. — A  common  parasite  in  the  rectum 
of  hosrs.  Found  sometimes  in  human  intestine. 

o 

FLAGELLATE. — Infusorial  organisms  with  lashlike  cilia. 
— .Family,  Monadina.  Round  or  oval.  Transparent.  A 
single  or  few  whiplike  hairs  on  anterior  extremity. 

Cercomonas. — With  caudal  filament  and  generally  a 
single  thin  and  long  lash. 

C.  Intestinalis.  —  Found  in  the  stools  of  cholera  and 
typhoid  fever,  and  on  catarrhal  mucous  membrane  of 
children. 

C.  Urinarius. — Urine  of  cholera  and  in  alkaline  albu- 
minous urine. 

C.  Saltans. — On  the  dirty  surface  of  ulcers. 

Trichomonas. — With  two  or  three  short  cilia  near  the 
anterior  lash. 

T.  Vaginalis. — In  the  yellow  acrid  mucus  of  vaginal 
blennorrhoea. 

II.  VERMES  ( Worms). 

1st  Class.  Platodes — Platyelmia. — Flat  worms.  Bodies 
flat,  appendages,  when  present,  of  suckers  and  hooks. 
Generally  hermaphrodite.  Many  without  mouth  or  in- 
testine, nourished  by  absorption. 

1st  Order.  Cestodes. — Tapeworms.  Long,  articulated, 
flat,  without  mouth  or  alimentary  canal.  Prehensile  or- 
gans anterior.  The  anterior  part  or  head  is  small  and 
somewhat  globular.  The  neck  is  thinner.  The  joints 
lengthen  and  broaden  in  continuous  succession  until  they 
reach  their  greatest  circumference  at  the  posterior  ex- 
tremity, where  they  may  separate  and  live  independently 


332  THE    MICROSCOPIST. 

as  proglottides.  The  cellular  connective  parenchyma  in- 
dexes in  its  periphery,  especially  on  the  head,  small  chalky 
concretions,  in  all  parts  the  ramifications  of  a  water-vas- 
cular system,  and  in  the  central  parts  the  sexual  organs. 
Each  segment  has  its  special  male  and  female  organs  of 
generation. 

Human  tapeworms  exhibit  a  complicated  metamorpho- 
sis connected  with  alternate  generation.  Generally  the 
ova  with  the  proglottides  pass  from  the  intestines  and 
are  conveyed  with  food  into  the  stomach  of  an  animal. 
The  embryos  become  free  in  the  stomach,  and  by  their 
movable  booklets  bore  their  way  into  the  bloodvessels 
and  are  deposited  in  various  organs,  as  the  liver,  muscles, 
brain,  etc.  Here  they  become  encapsulated  and  grow  into 
larger  vesicles,  each  of  which  is  a  cystworm.  From  its 
covering  one  (cysticercus)  or  several  (echinococcus)  nodu- 
lar depressions  grow  into  the  interior,  on  the  bottom  of 
which  is  the  armament  of  the  tapeworm's  head,  in  form 
of  suckers  and  hooks.  The  transportation  into  the  human 
stomach  is  effected  by  means  of  food,  especially  measled 
meat.  The  cyst  is  digested  and  the  head  of  the  tapeworm 
set  free  as  a  Scolex.  This  enters  the  small  intestine,  be- 
comes fixed,  and  develops  by  gradual  formation  of  seg- 
ments the  tapeworm  body. 

Family.  Tceniadce. — Head  pear-shaped  or  conoidal,  with 
four  round  suckers.  A  rostellum  or  wreath  of  hooks  be- 
tween the  suckers  or  anterior  part  of  head.  Proglottides 
distinctly  separate  and  generally  longer  than  broad. 

A.  Vesicular  tapeworms,  Cysticce.  Head  rarely  un- 
armed (T.  mediocanellata\  generally  with  rostellum  and 
hooks.  Middle  stern  of  uterus  gives  off  ramifying  side- 
branches.  Openings  of  sexual  apparatus  on  the  border, 
alternate  on  each  side. 

a.  Vesicular  tapeworms,  whose  heads  are  formed  in 
the  embryonal  state. 

1.  Tania  Solium. — Single,  or  several  together  in  small 


THE    MICROSCOPE    IN  AETIOLOGY.  333 

intestine.  Develops  to  from  two  to  three  meters  long,  and 
its  proglottides  ten  mm.  long  and  six  mm.  broad.  Head 
the  size  of  a  pin,  globular,  with  tolerably  prominent  suck- 
ers. Filamentous  neck,  almost  an  inch  long.  The  cyst  worm 
(Cysticercus  celluloses]  of  this  species  has  a  preference  for 
the  muscles  of  the  hog,  but  is  found  in  other  animals  and 
in  man. 

2.  Tee nia  Mediocanellata. — Larger  than  the  T.  solium. 
Head  without  a  circle  of  hooks  and  rostellum,  but  with 
powerful  suckers.     The  cystworm  inhabits  the  muscles  of 
cattle,  but  has  not  been  found  in  man. 

3.  T.  Acanthotrias. — The  vesicle  only  is  known.     Found 
in  muscles,  subcutaneous  tissue,  and  brain  of  man.     Hook 
apparatus  a  triple  circle  of  slender  claws. 

4.  T.  Marginata. — Mature  tsenioe  are  like  T.  solium,  but 
found  in  the  dog  and  wolf.     The  larva  abides  in  the 
omentum  or  liver  of  ruminants  and  swine,  and  sometimes 
of  man.     One  extremity  of  the  vesicle  is  drawn  out  in  a 
necklike  process,  which  contains  the  tapeworm. 

b.  Cyst  tapeworms,  whose  heads  bud  from  the  embry- 
onic capsules  of  the  inner  surface  of 'the  vesicle. 

5.  Tcenia  echinococcus  consists  of  only  three  or  four  seg- 
ments, the  last  of  which  exceeds  in  bulk  all  the  others. 
It  is  three  to  four  mm.  long,  and  its  thirty  or  forty  hook- 
lets  are  on  a  prominent  rostellum.     It  lives  in  the  intes- 
tine of  the  dog.     The  young  state  of  this  Tsenia  (echino- 
coccus) is  an  almost  motionless  vesicle  on  the  inner  sur- 
face, of  which  numerous  little  heads  bud  in  vesicles  the 
size  of  a  millet-seed.     These   are  sometimes  compound 
(daughter,  granddaughter  vesicles\  inclosed  one  within  the 
other.     In  this  form  they  are  found  in  man  and  cattle 
(especially  in  the  liver).     Other  animals  harbor  generally 
single  vesicles. 

B.  Common  tapeworms,  Cystoidece.  They  represent  no 
peculiar  larv?e.  Their  larvae  occur  only  in  cold-blooded 
animals  or  invertebrates.  Thus  the  cysticercoid  of  T. 


334  THE    MICROSCOPIST. 

elliptica  or  cucumerina  of  the  dog  live  in  the  lice  which 
infest  dogs,  and  the  dogs  are  infected  by  eating  these  lice. 
Clinical  ly,  they  are  less  important  than  cyst  tapeworms. 
Head  small  and  hook  apparatus  imperfect. 

a.  Head  prominence  with  a  single  circle  of  small  hooks. 

6.  Tcenia  Nana. — Small.     Anteriorly  filamentous,  but 
larger  near  the  middle.     Once  found  in  the  duodenum  of 
a  boy. 

7.  T.  Flavo  Punctata. — 33  cent.  long.    The  anterior  half 
of  immature  joints  0.2  to  0.5  mm.  long  and  1  mm.  broad, 
which  show  behind  the  middle  a  large  yellow  spot.     The 
receptaculum  filled  with  sperm.     Head  unknown. 

b.  Papilla  with  multiple  circle  of  hooks. 

8.  T.  Elliptica. — Usually  in  dogs  and  cats. 

Family  Bothriocephalidce. — Head  flattened.  Two  deep 
fissure-like  suckers.  Articulations  imperfectly  marked. 

9.  Bothriocephalus   Latus. — The   largest    human    tape- 
worm.    Sometimes  5  to  8  meters  long  arid  from  3000  to 
4000  short  and  broad  joints,  seldom  more  than  3.5  mm. 
long,  but  10  or  12  mm.  broad.     The  last  joints  are  nearly 
square.    Anterior  end  threadlike.    Proglottides  pass  away 
in  lengths  (from  2  to  4  feet).     Ova  oval,  with  transparent 
shells,  and  a  lid  at  one  end  through  which  the  embryo 
slips  into  the  water.     The  six-hooked  embryo  is  developed 
several  months  after  the  ova  are  passed. 

10.  B.  Cordatus. — Smaller  than  B.  latus.     Head  short 
and  broad,  heart-shaped. 

2d  Order.  Trematodes. — Suckerworms.  Parasitic  solitary 
flat  worms,  with  inarticulate  leaf-shaped  bodies  ;  with 
mouth  and  bifurcated  intestinal  canal,  without  anus, 
with  abdominal  prehensile  apparatus.  Male  and  female 
organs  mostly  in  the  same  individual.  The  distomata 
go  through  a  complicated  alternate  generation  and 
metamorphosis.  The  embryos  escape  from  the  ova 
into  water  and  seek  a  new  animal  habitat,  mostly 
snails.  Here  they  develop  into  cyst-germs,  which  are  the 
parents  of  the  Cercarice,  which  have  a  rudder-like  tail  and 


THE   MICROSCOPE    IN    ETIOLOGY.  335 

move  freely  in  the  water.  These  enter  a  new  aquatic 
animal,  snail,  worm,  crab,  or  fish,  pierce  into  the  tissues 
and  form  a  cyst.  Thus  the  young,  encysted,  sexless  disto- 
mata  arise  from  the  Cercariae,  the  former  received  with 
the  flesh  of  their  supporters  into  the  stomach,  and  thence 
freed  from  their  cyst  they  enter  other  organs  of  another 
animal,  where  they  become  sexually  mature. 

Gen.  Distomum. — Two  suckers  on  the  anterior  part. 
Genital  pores  near  the  abdominal  sucker. 

a.  Body  broad  and  leaf-shaped. 

11.  Distomum  Hepaticum. — Liver-fluke.     The  Cercarise 
are  probably  encapsuled  in  fresh- water  snails,  and  eaten 
by  sheep  infect  them..     The  perfect  D.  hepaticum  inhabits 
numerous  herbivorous  mammals  and  occurs  in  man. 

b.  Body  more  regular  in  form,  without  branched  in- 
testinal canal. 

12.  D.  crassum. 

13.  D.  Lanceolatum. — Both  extremities  pointed.    Asso- 
ciated with  D.  hepaticum  in  the  bile-ducts. 

14.  D.  Ophthalmobium. — Once  found  in  the  crystalline 
lens. 

15.  D.  heterophyes. 

c.  With  separate  sexual  apparatus.     Body  long  and 
slender.     Female  almost  cylindrical. 

16.  D.  Hcemalobium. — Oral  and  abdominal  suckers  equal 
in  size.     Color  white.     Is  frequent  in  Egypt,  in  the  veins 
as  well  as  intestinal  canal  and  bladder.     Feeds  on  the 
blood. 

Gen.  Monostomum. — Has  no  abdominal  sucker. 

17.  Monostomum  Cutis. — Found  once  in  the  lens. 

2d  Class.  Nematelmia. — Roundworms.  Bodies  rounded, 
pouched,  or  filamentous,  without  rings  or  segments. 
Sometimes  with  papillee  or  hooks  on  anterior  pole  Sexes 
distinct. 

1st  Order.  Acanthocephali  — Vertex  bearing  hooks.  No 
mouth  or  intestine. 


336  THE    MICROSCOPIST. 

18.  Echinorrhynchiis. — Inhabits  the  intestine  of  several 
vertebrates.     One  found  in  a  leucaemic  child. 

2d  Order.  Nematodes. — Threadworms.  Bodies  round, 
threadlike,  with  mouth  and  intestine.  Armament,  when 
present,  of  papillae  or  spikelets  and  hooks  within  the 
mouth.  Development  by  single  metamorphosis,  yet  many 
young  forms  have  an  abode  altogether  different  from  that 
of  their  parents,  and  often  the  young  and  sexually  mature 
inhabit  different  organs  or  different  animals.  Some  live 
parasitically  in  plants. 

\st  Sub- order.  Strong  yloidce. — JSTernatodes  with  anus. 

1st  Family.  Ascarides. — Mouth  with  three  lips  or  pa- 
pillae. Sometimes  teeth  in  the  throat.  Most  lay  hard- 
shelled  eggs. 

19.  Ascaris    Lumbricoides. — Roundworm.     Cylindrical 
body.     Male  250  mm.  by  3  mm.     Female  400  mm.  by  5.5 
mm.     Tail  of  male  conical  and  hooked. 

20.  A.  Mysto.x. — Smaller  than  the  preceding.    Identical 
with  the  common  round  worm  of  cats. 

21.  Oxyuris  Vermicular  is.  —  Threadworm.     Body   fila- 
mentous, white.     Three  lips  on  the  head.     Inhabit  chiefly 
the  rectum  and  large  intestine,  but  may  wander  to  vagina. 

2d  Family.  Strongyloidce. — Mouth  generally  armed  with 
a  horny  surface  or  hooks. 

22.  Strongylus  Gigas. — Long  red  worm.     Viviparous. 
In  the  pelvis  of  the  human  kidney. 

23.  S.  Longevaginatus. — Filamentous,  white. 

24.  S.  Armatus. — Cause  of  the  so-called   colic  of  the 
horse,  which  is  really  aneurism  of  the  intestinal  arteries. 

25.  S.  Duodenalis. — -Body   cylindrical.     Mouth   wide, 
with  two  claw-shaped  hooks.     In  Italy  and  Egypt  found 
in  the  intestines  by  thousands.     Gives  rise  to  anaemia,  etc. 

3d  Family.  Trichotrachelidce.— Moderately  large,  longi- 
tudinally striated  worms. 

26.  Trichocephcdas  Dispar. — Long  threadworm.     Body 
short,  2  cent,  long  by  1  mm.  thick,  with  filiform  neck, 


THE    MICROSCOPE    IN    AETIOLOGY.  337 

20  to  25  mm.  long,  and  head;  in  the  male  spiral,  in  the 
female  straight.  Generally  found  in  the  colon  of  children 
or  adults. 

27.  Trichina  Spiralis.—Ou  the  second  day  after  eating 
raw  flesh  containing  trichinae,  and  after  digestion  of  the 
inclosing  capsule,  the  worm  is  sexually  mature      Copula- 
tion occurs,  and  on  the  sixth  day  after  the  females  bring 
forth  each  about  1000  filamentous  embryos.    These  pierce 
the  intestinal  wall  and  wander  through  the  tissues  to  the 
voluntary  muscles,  where  they  coil  up  spirally  and  be- 
come encysted.     The  cysts  may  become  hard  and  even 
calcify.     In  this  state  they  may  remain  for  years  capable 
of  development.      The   hog    is   considered   the   original 
bearer  of  trichinae,  whence  they  have  infected  other  ani- 
mals. 

4.  Family.  Filaridce. — Long  filamentous  body. 

28.  Filaria   Medicensis. — Threadworm.      Guineaworm. 
Inhabits  the  subcutaneous  tissue  of  the  foot.   Found  only 
in  tropical  countries. 

3d  Class.  Annelidce. —  Ringed  worms.  Cylindrical  or 
flattened.  Segmented  body  with  brain,  oesophageal  ring, 
chain  of  abdominal  ganglia  and  bloodvessels. 

Order  Hirudinis. —  Leech.  Body  with  narrow  rings 
and  terminal  disk.  No  feet.  Hermaphrodite. 

Sub-order  Gnathobdellce. — Gill-leach.  Throat  with  three 
often  dentated  gills.  A  sort  of  oval  sucker  disk  in  front 
of  the  mouth.  Blood  mostly  red. 

29.  Hirudo  Medicinalis.—tiO   to  90   fine  teeth  on  the 
free  border  of  the  gills.     Is  three  years  in  arriving  to 
sexual  maturity. 

III.    ARTHROPODA. 

Animals  laterally  symmetrical.  Bodies  segmented. 
Limbs  articulate.  Brain  and  abdominal  ganglia  present. 
Propagation  generally  sexual. 

22 


338  THE    MICROSCOPIST. 

Class  Arachnidce. — Air-breathing.  Head  and  thorax 
blended.  No  feelers.  Two  pairs  of  jaws  and  legs.  Ab- 
domen without  members.  Sexes  distinct. 

Order  Linguatulidce  (Pentastomidee). —  Worm-shaped, 
ringed.  Mouth  rounded,  with  horny  border.  Four  legs, 
hooklike  and  sheathed.  Surface  hard  and  pierced  by 
stigmata.  Metamorphosis  complete. 

30.  Pentastomum  Tcenioides. — Inhabits  the  nasal  cavities 
of  the  dog  and  wolf.     The  larva  have  been  found  in  man. 

31.  Pentastomum   Denticulatum. —  Encapsuled,   curved, 
calcified.     On  the  surface  of  the  liver,  etc. 

Order  Acarince. — Mites.  Body  compact,  inarticulate. 
Mouth  for  biting,  sucking,  or  stinging.  Respiration  by 
tracheae. 

Family  Dermatophili. — Hair-follicle  rnite.  Elongated. 
Worm-shaped,  fringed  abdomen.  Suckers  and  stiletto- 
shaped  jaws.  Four  pairs  of  short  bipartite  feet. 

32.  Acarus    Folliculorum   (Dermodex   Folliculorum). — 
Found  often  in  ear-wax  and  sebaceous  glands  of  face. 

Family  Acaridce. —  Mites.  Microscopic,  soft-skinned. 
Legs  short,  with  disks  for  prehension. 

33.  Acarus,   or    Sarcoptes   Scabiei.  —  Itch-mite.      Body 
round,  arched,  with  transverse  striae  covered  with  spines 
and  bristles.     Young  have  but  one  pair  of  feet. 

Family  Ixodce. — Ticks.  Larger,  blood-sucking  mites, 
with  firm  back-shield  and  dentated  mandibles.  Live  on 
plants,  and  occasionally  on  man.  The  female  inserts  its 
proboscis,  and  fills  itself  with  blood,  causing  pain  and 
suppuration.  There  are  several  species. 

Family  Trombididce. — Running  mites.  Body  brightly 
colored,  covered  with  hair.  They  live  on  plants,  etc.,  but 
sometimes  on  man.  The  Leptus  autumnalis,  gooseberry 
or  harvest  mite,  is  often  troublesome  in  summer. 

Class  Hexapoda. — Insects. 

Order  Rhynchota. 

Sub-order  Aptera. — Wingless  insects,  with  short,  turned- 


THE    MICROSCOPE    IN    .ETIOLOGY.  339 

in,  fleshy  beak,  and  piercing  bristles,  or  with  rudimentary 
biting  mouth.  Body  has  usually  nine  articulations. 

Pediculus  Capitis. — Head-louse. 

P.  Pubis  or  Phthirius  Ingidnalis. — Crabs. 

P.  Vestimenti. — Clothes -louse. 

Sub-order  Hemiptera. 

Cimex  Lectularius. — Bed-bugs. 

Order  Diptera. — Insects  with  mouths  for  piercing  or 
sucking.  Inarticulate  thorax,  with  cuticular  anterior 
wings.  Swing-bats  for  posterior  wings.  Complete  meta- 
morphosis. 

Palex  Irritans. — Flea. 

Pulex  or  Dermatophilus  Penetrans. — Sand-flea.  Native 
of  South  America.  Breeds  under  the  cutis,  and  the  ova 
develop  in  the  sand. 

(Estrus  Hominis. — Gad-fly.  May  deposit  ova  in  skin  of 
man,  producing  boils. 

Musca  Vomitoria. — Large,  blue-bottle  fly. 

M.  Sarcophaga. — Common  flesh-fly. 

M.  Domestica. — House-fly. 

All  may  deposit  ova  or  fully  formed  larva  in  cavities 
and  wounds. 

V.   DISEASE  GERMS. 

The  germ-theory  of  disease  ascribes  disease,  particularly 
infectious  disease,  to  the  introduction  of  minute  parasitic 
organisms  into  the  tissues  of  the  body,  and  their  subse- 
quent multiplication  there.  Many  of  the  early  natural- 
ists entertained  substantially  this  view,  as  Vallisneri, 
Reaumur,  and  Linnaeus.  It  was  considered,  however,  but 
a  mere  hypothesis,  until  recent  microscopic  observations 
have  revived  an  interest  in  this  direction.  Liebermeister, 
in  his  recent  monograph  on  typhoid  fever,  says,  "  Within 
the  last  ten  years  a  great  revolution  has  taken  place  with 
regard  to  the  popular  signification  of  a  contagium  vivum. 
New  investigations  on  the  appearance,  mode  of  propaga- 


340  THE    MICROSCOPIST. 

tion,  and  the  significance  of  the  low  organisms,  new  facts 
in  regard  to  the  extension  of  national  diseases,  and  also  a 
number  of  quite  positive  discoveries  by  numerous  investi- 
gators, have  removed  the  old  opposition  to  the  theory,  or 
even  been  the  means  of  furnishing  definite  proof  of  its 
correctness."  This  quotation  expresses  the  most  san- 
guine views  of  the  adherents  of  this  theory. 

We  have  already  referred  to  the  connection  of  mould 
and  yeast  fungi  with  the  process  of  fermentation,  and  it 
is  quite  possible  that  the  introduction  of  such  germs  into 
the  body  may  produce  slight  irritations  and  even  inflam- 
mations from  the  increase  and  multiplication  of  the  fungi, 
and  the  chemical  changes  induced  by  them.  We  have 
also  seen  that  fungi  are  causes  of  putrefaction  as  well  as 
of  fermentation  in  organic  bodies.  Yet  the  diseases  of 
the  human  body,  in  which  fungi  have  been  proved  to  be 
real  causes,  are  but  few.  Among  vegetable  diseases 
caused  by  fungi  are  the  rust,  smut,  etc.,  of  our  grains,  the 
"  vine  disease,"  "  potato  disease,"  etc.  Among  animal 
diseases  of  this  kind  are  some  affections  of  caterpillars, 
flies,  etc.,  and  gangrene  of  the  spleen  in  mammals.  In 
splenic  gangrene,  however,  as  well  as  in  mycosis  intesti- 
nalis,  pyaemia,  diphtheria,  etc.,  in  which  fungi  occur,  the 
bacteria  may  be  merely  the  carriers  of  the  disease,  or  may 
develop  because  of  special  pabulum  furnished  by  the  dis- 
eased structure  which  is  not  present  in  the  normal  state. 

Another  theory  of  disease  germs  has  been  published  by 
Dr.  Eeale,  which  regards  them  as  minute  masses  of  de- 
praved bioplasm,  originated  probably  in  man's  own  body, 
or  in  the  bodies  of  some  of  the  animals  domesticated  by 
man. 

Both  theories  may  be  true  in  reference  to  the  cases  to 
which  they  are  applicable.  They  do  not  even  necessarily 
exclude  each  other.  Each  kind  of  disease-germ,  bioplastic 
or  fungoid,  may  have  a  range  of  action  peculiarly  its  own. 

Dr.  Beale's  views  seem  to  apply  to  a  much  wider  field 


THE    MICROSCOPE    IN    ETIOLOGY.  341 

of  research  than  the  other,  and  are  therefore  given  here 
in  abridged  form. 

Dr.  Beale  objects  to  calling  disease-germs  parasites, 
since  parasites  are  organisms  themselves,  and  not  mere 
particles  of  living  matter.  He  freely  admits  the  great 
variety  and  rapid  growth  of  microscopic  fungi  and  algae, 
and  the  readiness  with  which  they  may  enter  and  traverse 
the  textures  of  the  body,  but  considers  them  to  be  but 
seldom  the  cause  of  disease.  He  says,  "  In  every  part  of 
the  body  of  man  and  the  higher  animals,  and  probably 
from  the  earliest  age,  and  in  all  states  of  health,  vegetable 
germs  do  exist.  These  germs  are  in  a  dormant  or  quies- 
cent state,  but  'may  become  active  and  undergo  develop- 
ment during  life  should  the  conditions  favorable  to  their 
increase  be  manifested.  There  is  not  a  tissue  in  which 
these  gerrns  do  not  exist,  nor  is  the  blood  of  man  free 
from  them.  They  are  found  not  only  in  the  interstices  of 
tissues  but  they  invade  the  elementary  parts  themselves. 
Multitudes  infest  the  old  epithelial  cells  of  many  of  the 
internal  surfaces,  and  grow  and  flourish  in  the  very  sub- 
stance of  the  formed  material  of  the  cell  itself.  In  many 
very  different  forms  of  disease  these  germs  of  bacteria, 
and  probably  of  many  fungi,  are  to  be  discovered  in  the 
fluids  of  the  body,  but  the  evidence  yet  adduced  does  not 
establish  any  connection  between  the  germs  and  the  mor- 
bid process.  The  diseases  known  to  depend  upon  the 
growth  and  development  of  vegetable  organisms  are  local 
affections,  and  the  structure  of  the  organism  can  be  made 
out  without  difficulty,  but  contagions  are  general  affec- 
tions, and  no  such  success  attends  our  efforts  to  prove 
that  vegetable  organisms  are  the  active  agents.  In  fact, 
the  fungi  which  commonly  grow  on  the  surface  and  in 
other  parts  of  the  body  do  not  produce  disease.  The  germs 
of  fungi  may  remain  perfectly  passive  in  healthy  textures, 
growing  and  multiplying  only  in  those  which  have  already 
deteriorated  in  consequence  of  disease  or  old  age."  . 


342  THE    MICROSCOPIST. 

We  have  already  considered  Dr.  Beale's  views  respect- 
ing bioplasm — page  118 — as  the  forming  material  of  the 
tissues.  At  page  246  we  have  also  referred  to  his  doctrine 
of  inflammation,  etc.  These  views  will  prepare  us  to 
understand  the  theory  of  "  disease-germs,"  considered  as 
degraded  particles  of  bioplasm.  "  Degradation  in  power 
is  commonly  associated  with  increased  rate  of  growth,  and 
with  remarkable  vitality.  The  actively  living  degraded 
bioplasm  may  retain  its  vitality  although  removed  from 
the  living  body,  and  it  may  grow  and  at  length  destroy 
other  living  organisms  to  which  it  gains  access."  Animal 
fluids  and  secretions,  normal  as  well  as  those  known  to 
have  contagious  properties,  contain  minute  particles  of 
bioplasm,  which  are  sometimes  so  small  as  to  require  the 
highest  microscopic  powers  to  render  'them  visible,  yet 
they  are  capable  of  growth  and  multiplication  to  a  vast 
extent,  so  that  a  minute  particle  of  vaccine  or  other  lymph 
may  originate  important  changes  in  a  large  number  of 
persons. 

The  virulent  poison  of  dissection-wounds  cannot  be  as- 
cribed to  vegetable  germs,  since  it  is  most  virulent  shortly 
after  death  of  the  subject  of  dissection,  and  when  putre- 
factive decomposition  has  taken  place,  and  bacteria  swarm, 
the  real  contagious  virus  is  dead.  Such  is  the  vitality, 
however,  of  some  forms  of  degraded  bioplasm,  that  they 
will  not  only  multiply  on  mucous  surfaces,  but  live  long 
after  their  removal,  as  in  purulent  ophthalmia,  gonor- 
rhceal  pus,  etc.,  so  that  they  may  be  transported  in  vari- 
ous ways  from  one  place  to  another  and  still  retain  their 
multiplying  power.  A  very  small  portion  of  blood,  serum, 
or  of  the  tissues  of  an  affected  animal  is  sufficient  to 
propagate  cattle-plague.  Even  the  breath  of  the  diseased 
organism  contains  numerous  virulent  particles.  There  is 
reason,  also,  for  thinking  that  a  single  epithelial  cell  may 
contain  multitudes  of  active  particles  in  the  case  of  syphi- 
litic poison  which  may  remain  dormant,  perhaps  for  years, 


THE    MICROSCOPE    IN    J3TIOLOGY.  343 

or  may  from  time  to  time  give  rise  to  changes  peculiar  to 
it.  Particles  of  living  tubercle  may  be  so  minute  as  to  be 
carried  in  the  atmosphere,  although  tubercle  is  not  emi- 
nently contagious.  As  to  cancer  germs,  many  circum- 
stances render  it  improbable  that  they  can  be  transmitted, 
so  that  living  disease  germs  differ  remarkably  in  vital 
power  as  well  as  forms  of  activity.  Yet  they  resemble 
each  other  in  general  appearance.  Neither  by  its  form, 
chemical  composition,  or  other  demonstrable  properties, 
can  the  vaccine  germ  be  distinguished  from  the  small-pox 
germ,  or  the  pus  germ  from  either.  All  are  like  the 
minute  particles  of  bioplasm  of  the  blood,  from  which 
they  differ  so  remarkably  in  power.  Of  the  conditions 
under  which  these  germs  are  produced,  and  of  the  manner 
in  which  the  rapidly  multiplying  matter  acquires  its  new 
and  marvellous  specific  powers,  we  have  very  much  yet 
to  learn.  For  the  manner  of  detecting  these  germs  in  the 
air,  etc.,  see  the  former  part  of  the  present  chapter.  Mr. 
Lister's  excellent  plan  for  the  antiseptic  treatment  of 
wounds,  and  especially  the  results  of  carbolic  acid  spray 
in  surgical  operations,  together  with  many  posititive  ex- 
periments, show  that  carbolic  acid  has  a  powerful  action 
in  arresting  vital  phenomena  or  destroying  bioplasm.  In 
its  presence  embryonic  life  is  impossible ;  under  its  power- 
ful influence  all  minute  forms  of  life  perish.  Dr.  Beale, 
also,  refers  to  the  effects  of  carbolic  acid,  and  sulpho-car- 
bolates  administered  internally,  in  checking  the  too  rapid 
growth  of  bioplasm  in  the  blood  and  tissues,  as  well  as  to 
the  importance  of  disinfectants,  or  the  destruction  of  dis- 
ease germs  in  the  air,  sewage,  etc. 

Among  the  strongest  objections  to  the  theorjr  of  fungoid 
disease  germs  are  those  given  by  Dr.  Bastian  (a  strong 
supporter  of  spontaneous  generation),  that  the  theory  de- 
mands a  belief  in  the  existence  of  organisms  never  known 
in  their  mature  state,  and  whose  existence  is  not  demon- 
strated but  merely  presumed ;  that  such  germs  have  been 


344  THE    MICROSCOPIST. 

experimentally  shown  to  be  incapable  of  producing  the 
diseases  they  are  assumed  to  cause ;  and  that  feeding  on 
putrid  flesh,  swarming  with  bacteria,  as  the  Kalmucks  do 
habitually,  produces  no  injurious  consequences.  These 
objections  do  not  apply  to  the  theory  of  disease  germs 
advanced  by  Dr.  Beale,  while  it  will  be  found  to  accord 
with  the  most  careful  and  thorough  investigation's  in 
biology  and  pathology.  Yet  Beale's  views  have  received 
less  attention  than  they  deserve,  perhaps  because  of  his 
pronounced  antagonism  to  the  evolutional  philosophy, 
which  is  so  commonly  taught  under  the  guise  of  natural 
science. 


APPENDIX.  345 


APPENDIX. 

RECENT   ADDITIONS   TO    THE    MICROSCOPE    AND   MICROSCOPIC 
TECHNOLOGY. 

OPTICIANS  and  microscopists  strive  continually  after 
absolute  perfection  in  their  instrumental  means  of  re- 
search, so  that  every  little  while  some  new  piece  of  ap- 
paratus or  new  method  is  announced.  The  most  impor- 
tant recent  additions  are  named  here. 

« 

IMPROVEMENTS   IN   MECHANISM. 

Some  notable  improvements  have  been  added  to  first- 
class  instruments.  Zentmayer's  "Centennial"  model  has 
a  peculiarly  swinging  mirror  and  sub-stage.  The  mirror- 
bar  is  pivoted  in  the  plane  of  the  object  on  the  stage,  so 
that  illuminating  appliances  in  the  sub-stage  may  be 
effected  at  every  angle  of  inclination,  and  may  even  be 
brought  above  the  stage  as  a  condenser  for  opaque  objects. 
Mr.  Bullock,  of  Chicago,  has  also  adopted  a  similar  plan 
in  his  first-class  instruments,  and  the  Bausch  &  Lomb 
Optical  Company,  of  Rochester,  New  York,  place  a  swing- 
ing-bar below  the  glass  stage  of  their  "Professional" 
stand,  which  instrument  has  many  excellent  qualities, 
although  it  does  not  reach  the  idea  proposed  by  Zent- 
mayer. 

The  latter  optician  has  also  adopted  this  mechanism  in 
a  cheaper  form  for  students  in  his  "  Histological  Micro- 
scope." The  "Physician's  Microscopes,"  of  the  Bausch 
&  Lomb  Company,  are  also  models  of  cheapness  and  ex- 
cellence. Beck's  "National"  microscopes  are  among  the 
best  educational  stands. 


346  THE    MICROSCOPIST. 


IMPROVEMENTS   IN   OBJECTIVES. 

A  laudable  desire  to  place  really  good  objectives  in  the 
hands  of  students  at  a  reasonable  price  has  led  to  great 
emulation  among  opticians.  Spencer,  Tolles,  Wales,  Gund- 
lach,  and  the  Bausch  &  Lomb  Company,  in  addition  to 
their  most  perfect  objectives,  both  dry  and  immersion, 
which  must  necessarily  demand  a  high  price,  have  pre- 
pared others  at  less  cost  for  professional  and  students' 
use,  which  are  worthy  of  all  praise.  Some  of  them  fall 
but  little  below  the  performance  of  the  very  best  glasses. 

Test-objects,  such  as  those  referred  to  at  page  56,  and 
which  formerly  required  objectives  of  best  workmanship 
and  highest  power,  are  now  resolved  by  a  large  number 
of  objectives.  The  J-inch  of  Spencer  or  Tolles,  the  ith  of 
Gundlach,  and  even  a  T40th  of  Bausch  &  Lomb,  with  proper 
eye-pieces  and  illumination,  will  exhibit  nearly  all  which 
can  be  desired,  yet  powers  of  from  Jth  to  T'6th  are  still 
better.  For  refined  histological  work  2'gth  or  -^th,  or 
even  ^gth  inch  (Tolles),  will  be  found  most  useful. 

The  desire  to  obtain  the  largest  angle  of  aperture  possi- 
ble has,  however,  led  to  a  reduction  of  the  working  dis- 
tance, or  the  distance  between  the  object  and  front  of  the 
objective,  so  that  only  the  thinnest  covers  can  be  used. 

For  immersion  objectives,  also,  a  variety  of  fluid  media 
have  been  proposed,  as  glycerin,  castor  oil,  oil  of  cedar, 
and  kerosene. 


IMPROVEMENTS   IN   EYE-PIECES    AND   AMPLIFIERS. 

Periscopic  eye-pieces,  consisting  of  a  piano  or  double 
convex  field  lens  and  an  achromatic  meniscus,  have  been 
brought  to  great  perfection  by  E.  Gundlach  and  the  Bausch 
&  Lomb  Company.  Solid  eye-pieces  by  Tolles  have  also 
found  favor.  I  have  made  some  improvement  in  field  of 
view  and  definition  by  substituting  a  meniscus  for  the 


APPENDIX.  347 

field-glass  of  the  periscopic  eye-piece.  The  amplifier  re- 
ferred to  at  page  26,  or  an  achromatic  concave  meniscus, 
is  added  to  this  form  of  eye-piece  about  three  inches  from 
the  field-glass.  I  find  this  to  give  better  definition  than 
the  amplifiers  of  Zentmayer  and  Tolles,  which  are  placed 
at  the  end  of  the  draw-tube. 

IMPROVEMENTS    IN   ILLUMINATORS. 

Most  of  the  improvements  suggested  in  illuminators 
have  been  connected  with  oblique  light.  In  Amici's  prism, 
Nachet's  prism,  Reade's  condenser,  etc.,  the  purpose  is  to 
utilize  oblique  light  and  exclude  central.  In  the  illumi- 
nator proposed  at  page  35  I  have  combined  a  condenser 
with  an  illuminating  prism.  Mr.  Edmunds  (after  Mr. 
"YVenham)  has  contrived  a  paraboloid  lens  with  the  front 
cut  off  flat  and  polished.  This  is  in  fluid  contact  with 
the  under  side  of  the  slide.  Mr.  Wenham's  reflex  con- 
denser, although  difficult  to  use,  is  capable  of  excellent 
effects.  A  small  lens  (plano-convex)  placed  in  immersion 
contact  with  the  under  side  of  the  slide  is  also  used.  Dr. 
Woodward's  prism,  however,  for  effectiveness  and  cheap- 
ness, bids  fair  to  surpass  them  all.  This  is  a  small  right- 
angled  prism,  with  its  base  in  immersion  contact  with  the 
slide,  receiving  the  light  from  the  mirror  or  condenser  at 
right  angles  to  the  facet. 

The  hemispherical  condenser  and  oblique  illuminator  of 
Mr.  Gundlach,  attached  to  the  "Professional"  microscope 
of  the  Bausch  &  Lomb  Company,  are  also  well  adapted 
for  the  purpose. 

DOUBLE-STAINED    PREPARATIONS. 

Sections  of  vegetable  tissues  present  a  beautiful  appear- 
ance under  the  microscope  when  doubly  stained.  They 
should  first  be  soaked  in  alcohol,  if  green,  to  deprive  them 
of  chlorophyll,  then  subjected  to  a  solution  of  chloride  of 


348  THE    MICROSCOPIST. 

lime  ( J-  ounce  to  1  pint  of  water)  until  thoroughly  bleached. 
Soak  then  in  a  solution  of  hyposulphite  of  soda  (1  drachm 
to  4  ounces  water)  for  an  hour,  and  after  thoroughly  wash- 
ing in  several  changes  of  water  transfer  them  to  alcohol. 
Prepare  some  red  staining  fluid  by  dissolving  J  a  grain  of 
magenta  crystals  in  1  ounce  of  alcohol.  Soak  the  speci- 
men in  this  for  thirty  minutes,  then  rapidly  rinse  it  in 
alcohol  and  place  in  a  blue  fluid  made  by  dissolving  J 
grain  of  anilin  blue  in  1  drachm  of  distilled  water,  adding 
10  minims  of  dilute  nitric  acid  and  alcohol  enough  to 
make  2  ounces.  Let  the  specimen  remain  only  two  or 
three  minutes  in  this,  rapidly  rinse  in  alcohol,  put  in  oil 
of  cajeput,  thence  into  turpentine,  and  mount  in  balsam. 
The  principle  of  double  staining  depends  on  the  affinity 
which  certain  dyes  have  for  certain  cells.  Thus,  if  sec- 
tions stained  in  red  or  green  anilin  be  soaked  in  alcohol, 
and  those  stained  by  logwood  in  alum-water,  the  color 
will  leave  the  loose  parenchyma  and  be  retained  by  the 
denser  cells,  while  specimens  stained  in  blue  anilin  if  left 
in  alcohol,  and  those  stained  in  carmine  if  left  in  water, 
lose  color  more  slowly  in  the  parenchyma  than  in  other 
parts. 

Eosin-staining . — Dilute  solutions  of  eosin,  an  anilin 
preparation,  1  part  to  1000  of  wTater,  has  been  proposed 
for  animal  tissues,  since  the  different  parts  are  differenti- 
ated by  different  tints.  Sections  are  stained  in  a  minute 
to  a  minute  and  a  half,  then  washed  in  water  acidulated 
slightly  with  acetic  acid,  and  examined  in  glycerin;  or 
they  can  be  mounted  in  balsam  after  the  water  is  removed 
(see  page  80). 

CLASSIFICATION  OF  CRYPTOGAMIA. 

In  addition  to  the  classification  given  in  previous  chap- 
ters, the  following,  chiefly  compiled  from  the  Micrographic 
Dictionary ',  may  be  useful: 


APPENDIX.  349 


FERNS. 

Order  1.  POLYPODIACE.33.— Sporanges  on  lower  sur- 
face in  groups,  but  never  blended.  Annulus  present,  but 
variable. 

Family  I.   POLYPODIODIDE^E.— Numerous   sporanges  in 
sessile  sori,  divided  equally  by  a  vertical  annulus. 
A.  No  indusium. 

Tribe  1.  Polypodiece. — Sori  at  apices  of  veins. 

*  Veins  pinnate. 

f  Margins  of  fertile  fronds  not  revolute. 

Gen.  1.  Polypodium. — Sori  globose  on  apex  or  back  of 
veins  or  venules. 

Gen.  2.  Marginaria. — Sori  globose  immersed  deeply  in 
backs  of  veins  or  venules. 

Gen.  8.  Pleopeltis. — Sori  globose  on  backs  of  veins  or 
venules,  with  peltate  paraphyses  concealing  the  sporanges. 

t  f  Margin  of  fertile  fronds  revolute. 

Gen.  4.  Struthiopteris. — Sori  globose  on  backs  of  veins 
or  venules. 

*  *  Veins  anastomosing.     No  free  veins  in  the  areolse. 
Gen.   5.    Dictyopteris. — Sori   globose   on   anastomosing 

venules.     Venules  anastomosing  in  irregular  hexagonal 
spots. 

*  *  *  Veins  anastomosing.     Free  veins  in  areolse. 
Gen.  6.  Niphobolus. — Sori  globose  on  apex  of  venules. 

Venules  branched,  forming  transverse  rhomboid  spots. 

Tribe  2.  Acrostichece. — Sporangia  scattered  over  the 
whole  surface. 

Gen.  1.  Acrostichum. — Sori  on  all  the  veins  and  paren- 
chyma. Veins  branched  and  anastomosing. 

Gen.  2.  Campium. — Veins  branched,  with  free  venules. 


350  THE    MICROSCOPIST. 

Gen.  3.  Polybotrya. — Veins  pinnate,  scarcely  anastomos- 
ing. 

Tribe  3.  Tcenitidece. — Sori  linear,  extending  to  the  areolse 
of  the  leaves. 

Gen.  1.  Pleurogramma.  Sori  contiguous  on  each  side  of 
the  rib,  parallel,  linear,  and  continuous.  Veins  simple. 

Gen.  2.  Tcenitis. — Sori  submarginal  in  middle  of  disk 
of  leaf,  linear,  elongated,  and  continuous.  Veins  anasto- 
mosing into  meshes. 

Gen.  3.  Notholcena. — Sori  marginal,  linear,  continuous. 
Veins  pinnate. 

Tribe  4.  Grammitidece. — Sori  linear,  confined  to  the  veins 
or  veinlets. 

Gen.  1.  Grammitis. — Sori  linear  or  roundish,  seated  on 
certain  arms  of  the  veins.  Veins  simple  or  forked,  scarcely 
anastomosing. 

Gen.  2.  Selligncea. — Sori  linear  or  roundish,  on  certain 
arms  of  veins.  Veins  much  branched  and  anastomosing 
without  free  veins. 

Gen.  3.  Synamnia. — Sori  oblong,  on  back  of  lowest 
venule.  Veins  branched,  anastomosing,  with  free  venules. 

Gen.  4.  Meniscium. — Sori  reniform,  on  back  of  trans- 
verse venules.  Veins  pinnate,  anastomosing. 

Gen.  5.  Antrophyum. — Sori  imbedded  on  the  back  of 
all  the  veins  and  venules.  Veins  branched,  anastomos- 
ing. 

Gen.  6.  Hemionitis. — Sori  on  back  of  veins.  Veins 
branched,  anastomosing  in  regular  meshes. 

Gen.  7.  Gymnogramma. — Sori  on  back  of  veins.  Veins 
pinnate  or  forked,  scarcely  anastomosing. 

Tribe  5.  Vittariece. — Sori  in  the  grooved  margin,  which 
simulates  an  indusium. 


APPENDIX.  351 

Gen.  1.  Vittaria. — Sori  solitary.  Fronds  ribbonlike  or 
grassy. 

B.  With  an  indusium. 

Tribe  6.  Adiantece. — Sori  linear,  marginal,  at  apices  of 
veins.  Indusium  spurious,  formed  by  revolute  margin. 

*  Sori  on  the  notches  of  the  fronds. 

Gen.  1.  Lonchitis. — Veins  anastomosing.  Sori  linear, 
semilunate.  Indusium  marginal,  semilunar. 

Gen.  2.  Hypolepis. — Veins  primate.  Sori  sub-globose, 
on  inferior  border  of  teeth  of  frond.  Indusium  margi- 
nal, semilunar. 

*  *  Sori  on  margin  of  the  frond. 

Gen.  3.  Lomaria. — Veins  primate,  forked  ;  fertile  fronds 
narrower.  Sorus  linear,  continuous. 

Gen.  4.  Pteris. — Veins  primate.     Sorus  continuous. 

Gen.  5.  Amphiblestra. — Primary  veins  strong.  Venules 
anastomosing  in  hexagonal  spots.  Sorus  linear. 

Gen.  6.  Litobrochia. — Veins  anastomosing  hexagonally. 
Sorus  linear. 

Gen.  7.  Allosorus. — Veins  primate.  Sori  at  first  roundish, 
then  confluent  and  linear,  covered  by  the  reflected  margin. 

Gen.  8.  Cassebeera. — Veins  primate.  Sori  two  under 
each  notched  tooth  of  the  leaf. 

Gen.  9.  Adiantum. — Veins  fan-primate.  Sori  linear  or 
semilunar,  free  within. 

.  Gen.  10.  Hewardia. — Veins    reticulated.      Sori   linear. 
Indusium  linear  or  semilunar. 

Gen.  11.  Cheilanthes. — Veins  primate.  Sori  sub-globose, 
minute,  covered  by  reflexed  apex  of  tooth  and  the  indu- 
sium. 

Tribe  7.  Dicksoniece. — Sori  globose,  apical.  Indusium 
lateral,  two-valved. 

Gen.  1.  Dicksonia. — Valves  of  indusium  unequal. 
Gen.  2.  Cibotium. — Valves  nearly  equal. 


352  THE    MICROSCOPIST. 

Gen.  3.  Cystodium. — True  indusium  plane,  false  one 
hood  like. 

Gen.  4.  Thrysopteris. — Sori  serniglobose.  Indusium  cup- 
like.  Sori  on  a  thrjse  (leaf  without  parenchyma). 

Gen.  5.  Deparia. — Sori  as  in  4.  Parenchyma  of  leaf 
developed. 

Tribe  8.  Dawttiete. — Sori  apical,  inframargiual.  Indu- 
sium one-valved. 

Gen.  1.  Davallia. — Sori  globose.  Indusium  cup-shaped, 
the  mouth  truncated.  Veins  primate. 

Gen.  2.  Lindscea. — Sorus  linear,  continuous.  Indusium 
parallel  with  leaf  margin,  free  outside.  Veins  dichoto- 
mous. 

Gen.  3.  Dictyoxyphium. — Sorus  and  indusium  as  in  2. 
Veins  anastomosing  with  free  venules. 

Gen.  4.  Schizdoma. — Sorus  and  indusium  as  in  2.  Veins 
anastomosing  in  hexagonoid  meshes. 

Tribe  9.  Aspleniece. — Sori  on  veins.  Indusium  persist- 
ent, lateral,  the  margin  free. 

Gen.  1.  Scolopendrium. — Veins  primate.  Sori  linear,  in 
pairs  on  adjacent  sides  of  two  parallel  veinlets. 

Gen.  2.  Antigramma. — Veins  primate,  veinlets  anasto- 
mosing.    Sori  linear,  in  pairs  facing  together. 
.    Gen.  3.  Camptosorus.—  Veins  as  2.     Sori  elongated,  di- 
verging. 

Gen.  4.  Diplazium. — Veins  primate,  veinlets  free.  Sori 
linear,  in  pairs  back  to  back. 

Gen.  5.  Oxygonium. — Veins  primate,  veinlets  anasto- 
mosing at  the  ends.  Sori  as  4. 

Gen.  6.  Asplenium. — Veinlets  free.  Sori  linear,  single 
on  back  of  vein  or  veinlet. 

Gen.  7.  Ceterach. — Indusium  replaced  by  scales.  Sori 
linear  on  back  of  veins. 

Gen.  8.  Neottopteris. — Veinlets  anastomosing  at  ends. 
Sori  linear,  single. 


APPENDIX.  353 

Gen.  9.  Aihyrium. — Veins  primate.  Sori  straight, curved, 
or  reniform,  but  attached  by  a  linear  edge. 

Gen.  10.  Bleehuwn. — Sori  marginal,  somewhat  conflu- 
ent. Indusium  opening  inwards. 

Gen.  11.  Doodia. — Veins  parallel,  anastomosing  slightly. 
Sori  lunate  or  linear,  in  one  or  two  rows  parallel  with 
midrib.  Indusium  flat. 

Gen.  1 2.  Woodwardia. — Vein  lets  form  hexagonal  meshes. 
Sori  lunate  or  linear,  parallel  with  midrib  in  one  row. 
Indusium  convex,  immersed. 

Gen.  13.  Cystopteus. — Indusium  suborbicular,  fixed  by 
a  lateral  inferior  point. 

Gen.  14.  Onoclea. — Fertile  pinme  contracted  into  glob- 
ules. Indusium  lunate,  attached  on  a  short  horizontal 
veinlet. 

40 

Tribe  10.  Aspidiece. — Sori  subglobose.  Indusium  with 
central  or  eccentric  point  of  attachment,  free  all  round. 

Gen.  1.  Lastrcea. — Indusium  reniform.  Yeinlets  free 
at  ends. 

Gen.  2.  Nephrolepis. — Indusium  reniform.  Sori  on  tips 
of  upper  veinlets.  Petioles  articulated  with  the  rachis. 

Gen.  3.  Nephrodium.— Indusium  reniform,  veinlets  in- 
osculating. 

Gen.  4.  Aspidium. — Tndusium  orbicular,  peltate.  Veins 
branched,  anastomosing  hexagonally,  with  free  veinlets. 

Gen.  5.  Polystickum. — Indusium  orbicular,  peltate.  Sori 
on  middle  of  veins  below  the  bifurcations. 

Gen.  6.  Sagenia. — Indusium  orbicular,  peltate.  Vein- 
lets  anastomosing  hexagonally  without  free  ringlets. 

Gen.  7.  Fadyenia. — Indusium  cordate.  Sori  apical,  bi- 
seriate.  Veinlets  reticulate. 

Gen.  8.  Didymochlcena. — Indusium  oblong-elliptic,  fixed 
in  the  middle  by  a  longitudinal  crest. 

Gen.  9.  Matonia  — Indusium  orbiculate,  peltate,  umbo- 
nate,  the  margins  deflexed,  covering  about  six  sporanges. 

23 


354  THE    MICROSCOPIST. 

Tribe  11.  Peranemece. — Indusium  inferior,  ultimately 
lobed  or  ciliated. 

Gen.  1.  Peranema. — Sori  pedunculate.  Indusiura  cup- 
shaped,  splitting  into  2-4  lobes.  Sporanges  on  punctiform 
receptacle.  Veins  pinnate. 

Gen.  2.  Diacalpe. — Sori  regular.  Indusium  sessile, 
spherical,  at  first  closed.  Sori  on  a  punctiform  receptacle, 
then  bursting  irregularly  at  the  summit. 

Gen.  3.  Woodsia. — Sporanges  pedicellate,  inserted  at 
bottom  of  indusium  which  is  cup-shaped  and  hairy  at 
margin.  Veins  pinnate. 

Gen.  4.  Bypoderris. — Sporanges  on -almost  obsolete  axis- 
Indusium  cup-shaped,  fringed  at  margin.  Veins  anasto- 
mosing. 

family  II.  CYATH^EJE. — Numerous  sporanges,  united 
in  sori  on  a  salient  axis,  with  a  somewhat  oblique  annulus. 

A.  Sori  without  indusia. 

Gen.  1.  Alsophila. — Sori  globose,  regularly  arranged. 
Sporanges  on  globose  axis  and  imbricated. 

Gen.  2.  Trichopteris. — Sori  globose,  regularly  arranged, 
laterally  confluent.  Sporanges  on  globose  axis,  areolate 
and  crinite  with  long  hairs. 

Gen.  3.  Metaxya. — Sori  globose,  each  fertile  vein  bear- 
ing several,  irregularly  scattered.  Sporangia  on  globose 
axis,  beset  with  long  articulated  hairs. 

B.  Sori  indusiate. 

Gen.  4.  Hemitelia. — Sori  globose,  each  solitary  on  a 
pinnule.  Indusium  an  ovate,  concave,  torn  scale,  at  lower 
side  of  the  base. 

Gen.  5.  Cnemidaria. — Sori  globose,  regularly  arranged. 
Indusium  forming  an  involucre,  at  length  irregularly  torn 
or  partite. 

Gen.  6.  Cyathea. — Sori  hemispherical,  regular.  Indu- 
sium first  closed,  then  bursting  and  cup-shaped. 


APPENDIX.  355 

Gen.  7.  Schizoccena. — Sori  regular.  Indusium  of  six 
lobes  surrounding  the  globose  receptacle. 

Family  III.  GLEICHENIE^I. — Sporanges  united  in  fours 
into  sori,  and  surrounded  by  an  oblique  annulus,  like  a 
turban. 

Gen.  1.  Gleichemia. — Sporangia  in  roundish  sori.  Indu- 
sium absent.  Leaves  forking. 

Gen.  2.  Platyzoma. — Sporanges  in  pointlike  sori.  In- 
dusium spurious,  formed  by  revolute  margin  of  leaf, 

leaves  undivided. 
• 

Family  IV.  PARKERLELE. — Sporanges  ununited  into  sori, 
and  divided,  equally  by  a  vertical  annulus. 

Gen.  1.  Ceratopteris. — Sporanges  surrounded  by  a  broad, 
complete,  articulated  annulus,  placed  on  longitudinal 
veins.  Spores  globose,  trifariously  streaked. 

Gen.  2.  Parkeria. — Sporanges  with  almost  obsolete 
basilar  annulus,  or  longitudinal  veins.  Spores  three-sided, 
concentrically  streaked. 

Family  V.  OSMUNDEJE. — Sporanges  united  in  sori,  and 
covered  on  the  back  by  a  broad  and  imperfect  annulus. 

Gen.  1.  Osmunda. — Sporangia  on  metamorphosed  pin- 
nules. 

Gen.  2.  Todea. — Sporangia  on  unchanged  pinnules. 

Family  VI.  SCHIZ^EE^:.: — Sporanges  united  in  sori,  and 
annulus  like  a  skull-cap  with  radiating  streaks. 

Gen.  1.  Aneimia. — Sporangia  twin,  sessile  in  two  rows, 
on  lateral  lobes  of  leaf,  contracted  into  a  panniculate  im- 
marginate  rachis,  naked,  splitting  longitudinally  outside. 
No  indusium. 

Gen.  2.  Schiz&a. — Sporanges  sessile  in  two  or  four  rows 
in  linear  membranous-margined  lobes,  pectinately  oppo- 


356  THE    MICROSCOPIST. 

site  or  digitate  at  apex  of  leaf,  set  among  hairs,  splitting 
longitudinally  on  the  outside.  No  indusium. 

Gen.  3.  Lygodium. — Sporangia  sessile,  alternately  bi- 
seriate  on  marginal  lobes  of  leaf,  splitting  longitudinally, 
each  veiled  by  a  scalelike,  hood-shaped  indusium  adhering 
transversely  to  the  nerves. 

Gen.  4.  Mohria. — Sporangia  sessile  in  one  row,  close  to 
margin  of  leaf,  splitting  longitudinally  on  the  outside.  A 
spurious  indusium  formed  by  revolute  margin  of  leaf. 

Order  2.  MA  RATTIACE^.— Sporanges  on  lower  sur- 
face, usually  blended  together,  or  very  closely  approxi- 
mated. No  annulus. 

Gen.  1.  Angiopetris. — Sporangia  in  two  rows  near  apex 
of  transverse  veins,  distinct,  forming  linear  sori,  opening 
by  a  slit  on  outer  side.  No  indusium. 

Gen.  2.  Kaulfussia.  —  Sporangia  on  anastomoses  of 
veins,  radiately  connate,  forming  roundish  sori,  opening 
by  a  slit  at  apex. 

Gen.  3.  Marattia. — Sporangia  in  two  rows  near  apex  of 
transverse  veins,  connate,  forming  oblong  sori,  gaping 
transversely  by  a  vertical  slit.  Indusia  connate  with 
sori. 

Gen.  4.  JEupotium. — Sporangia  as  3,  but  pedicellate. 

Gen.  5.  Dancea. — Sporangia  in  two  rows,  near  trans- 
verse veins,  connate  into  linear  sori,  opening  by  a  pore. 
Indusia  superficial,  encircling  the  sori. 

Order  3.  OPHIOGLOSSE^E.— Sporanges  on  lower  sur- 
face of  leaf  (reduced  to  mere  ribs),  never  blended.  No 
annulus. 

Gen.  1.  Ophioglossum. — Sporanges  dehiscing  transversely, 
connate  on  an  undivided  distichous  spike. 

Gen.  2.  Botrychium. — Sporanges  as  last,  on  a  distichous, 
secund,  bi-tri-pinnate  spike. 

Gen.  3.  Helminthostackys. — Sporanges  dehiscing  exter- 


APPENDIX.  357 

nally,  vertically,  from  base  to  middle,  collected  in  whorls, 
with  crestlike  appendages,  and  stalked,  arranged  distich- 
ously  on  an  elongated  spike. 

Order  4.  HYMENOPHYLLE^E.— Sporanges  attached 
to  a  common  stalk,  prolonged  from  end  of  vein  of  leaf, 
and  contained  in  a  kind  of  cup  formed  by  a  lobe  of  leaf 
above  and  indusial  lobe  from  lower  surface  of  leaf. 
Obliquely  transverse  annulus. 

Gen.  1.  Trichomanes. — Sporanges  sessile  around  base  of 
an  exserted  filiform  column  projecting  from  margin  of 
leaf,  surrounded  by  a  cup  shaped  indusium  continuous 
with  leaf. 

Gen.  2.  Hyme.nophyllum. — Sporanges  sessile  up  to  sum- 
mit of  a  column  projecting  from  the  margin  of  the  leaf, 
sub-elevated,  but  not  exserted  beyond  the  indusium,  which 
is  two-valved. 

Gen.  8.  Loxsoma. — Sporanges  stalked,  inserted  up  to 
summit  of  a  sub-elevated  exserted  column  in  margin  of 
leaf,  surrounded  by  an  indusium,  with  truncated  mouth, 
entire. 

MICROSCOPIC    FUNGI. 

Order  COKIOMYCETES.— The  mycelium  may  be  short 
filaments  converted  into  spores,  or  a  flocculeut  patch  in 
decaying  matter  or  under  the  epiderm  of  plants,  or  more 
completely  organized  into  hollow  conceptacles  containing 
spore-bearing  filaments. 

Family  I.  SPHJERONEMEI. — Conceptacles  rising  from  mi- 
croscopic mycelia  growing  beneath  the  epidermis  of  leaves, 
stems,  etc.,  containing  a  chamber  lined  by  a  perithecium 
bearing  single,  often  septate  spores,  and  bursting  by  a  pore 
at  the  summit. 

Gen.  1.  Coniothyrium. — Conceptacle  free,  membranous, 
opening  by  an  irregular  pore  at  the  summit.  Spores 
globular. 


358  THE    MICROSCOPIST. 

2.  Leptostroma. — Conceptacle  innate,   subumbonate   in 
the  centre,  dimidiate,  at  length  falling  off,  leaving  a  thin 
disk. 

3.  Phoma. — Conceptacle    ostiolate,   very   thin,   innate, 
immersed,  rounded,  with  a  simple  pore.     Spores  oblong, 
simple. 

4.  Leptothyrium. — Conceptacle operculate,  innate,  shield- 
shaped,  not  radiate-fibrous.   Spores  spindle-shaped,  simple. 

5.  Aetinothyrium. — Conceptacle  operculate,  innate,  etc., 
as  4. 

6.  Microthecium. — Conceptacle indehiscent,  membranous, 
immersed,  endophytic.     Spores  simple. 

7.  Cryptosporium. — Conceptacle   membranous,  opening 
irregularly  at  summit.     Spores  spindle-shaped,  simple. 

8.  Sphceronema. — Conceptacle  horny,  inn-ate-superficial, 
produced   into   a   neck,  ostiole  simple.      Spores   oblong, 
simple. 

9.  Acrospermum. —  Conceptacle     leathery     externally, 
fleshy   within,   elongate-clavate,   ostiole  simple.      Spores 
stick-shaped,  simple. 

10.  Diplodia. — Conceptacle  horny,  innate-superficial  or 
immersed,  perforated  by  a  pore  or  irregularly  opened  or 
ostiolate,  ostiole  more  or  less  produced.     Spores  ovoid  or 
ellipsoid,   double,   then    halved   into   compressed-ternate 
semi-ellipsoid  sporules. 

11.  Hendersonia.  —  Conceptacle   fleshy,   innate  superfi- 
cially or  immersed,  perforated  by  a  pore,  opening  irregu- 
larly or  ostiolate,  ostiole  produced.    Spores  globose,  cylin- 
drical or  discoid. 

12.  Septoria. —  Conceptacle    horny,    innate-immersed, 
rounded,  ostiole  simple.     Spores  cylindrical,  septate. 

13.  Vermieularia.  —  Conceptacle     bristly,     depressed, 
bursting  irregularly.     Spores  minute,  linear. 

14.  Neottiospora. — Conceptacle  immersed.     Spores  ap- 
pendaged  at  one  end  with  short  hyaline  threads. 

15.  Asteroma. — Conceptacle  very  small,  slightly  promi- 


APPENDIX.  359 

neut,  close,  subconfluent,  seated  on  more  or  less  radiating 
fibrils. 

16.  Discosia. — Conceptacles  innate,  somewhat  carbona- 
ceous, at  length  collapsed  and  plicate,  ostiole  perforated. 
Spores  fusiform,  produced  at  both  ends  into  a  threadlike 
point. 

17.  Prosthemium. — Conceptacles   horny,  immersed,   os- 
tiole simple.     Spores  transversely  septate,  verticulate  at 
the  apex  of  thin  filaments. 

18.  Angiopoma.— Conceptacles  free,  membranous,  some- 
what horny,  cup-shaped,  dehiscing  by  a  circular  mouth, 
provided  with  a  fugarious  epiphragm.     Spores  affixed  at 
base,  stalked,  septate. 

19.  Piggotia. — Conceptacles  irregular,  thin,  obsolete  be- 
neath, confluent,  bursting  by  irregular  crack;  spores  on 
short  stalks,  largish,  obovate,  somewhat   constricted  at 
base. 

20.  Phlyctcena. — Conceptacle   spurious,   formed  by  the 
blackened  epidermis  ;  spores  fusiform,  cuspidate,  septate, 
accompanied  by  a  gelatinous  mass. 

21.  Glceosporium. — Conceptacle  absent ;  spores  covered 
by  cuticle  which  separates  ;  spores  stalked,  elliptical,  sim- 
ple, exuding  a  gelatinous  tendril. 

22.  Dilophosphora. — Conceptacle  immersed  in  a  spurious 
stroma,  covered,  perforated  by  a  pore ;  spores  cylindrical, 
continuous,  crowned  at  both  ends  with  radiating  filiform 
appendages. 

23.  Sphceropsis. — Conceptacle  spherical,  immersed,  sub- 
innate,  astomous,  bursting  by  separation  of  epidermis  or 
irregularly.     Spores  simple. 

Family  II.  MELANCONIEI. — Conceptacles  as  in  the  pre- 
ceding, but  without  a  proper  perithecium  ;  spores  elon- 
gated. 

Gen.  \.  Sporidia  globose,  simple,  adhering  to  form  a 
nucleus,  at  length  breaking  out  free.  Color  black. 


360  THE    MICROSCOPIST. 

2.  Papularia. — Sporidia  quite  simple, collected  in  groups 
under  epiderm  of  dead  plants,  set  free  in  a  pulverulent 
patch  by  the  decay  of  the  epidermis. 

3.  Stilbospora. — Sporidia  septate  (septa  evanescent),  full 
of  sporidiola,  adhering  in  a  nucleus,  at  length  breaking 
out. 

4.  Didymosporium. — As  the  last,  but  the  sporidia  didy- 
mous  (septate  in  middle).     Color  black  or  fuscous. 

5.  Cytispora. — Sporidia  simple,  stick-shaped,  minute,  in 
a  multilocular  nucleus,  at  length  opening  by  a  common 
apical  pore  and  emerging  as  a  gelatinous  tendril. 

6.  Melasmia. — Sporidia  minute,  stick-shaped,  in  a  flat, 
thin  nucleus,  which  bursts  at  apex  and  extrudes  the  spores 
in  a  gelatinous  globule. 

7.  Micropera. — Sporidia  linear,  curved,  formed  in  nu- 
clei, bursting  by  distinct  pores,  and  discharged  mixed  with 

jelly. 

8.  Ceuthospora. — Sporidia   simple,   ovate,  contained  in 
several  globose  nuclei  in  a  common  stroma,  escaping  by  a 
simple  lancinate  pore. 

9.  Nemaspora. — Sporidia  simple,  spindle-shaped,  in  nu- 
clei in  a  common  grumous  stroma  and  opening  by  a  com- 
mon pore. 

10.  Discdla. — Sporidia  elongated,  simple  or  uniseptate, 
stalked,  in  a  nucleus  with  perithecium. 

11.  Cylindrosporium    (Glceosporium). — Sporidia   simple, 
elliptical,  stalked,  in   nucleus  covered  only  by  cuticle  of 
leaf,  finally  extruded  in  a  gelatinous  tendril. 

12.  Coryneum. — Sporidia  spindle-shaped,  multiseptate, 
stalked,  crowded,  breaking  out  on  surface  as  a  pulvinate 
disk. 

13.  Bactridium. — Sporidia  spindle-shaped,  multiseptate, 
transparent  at  ends,  tufted  on  a  superficial  creeping  my- 
celium. 

14.  Eriospora. — Sporidia  filiform,  originally  attached  in 


APPENDIX.  361 

fours  upon  sporophores,  in  groups  of  globose  nuclei  open- 
ing by  a  common  pore. 

15.  Cheirospora. — Sporidia  simple,  crowded  in  tufts  at 
apex  of  a  filiform  sporophore,  in  moniliform  rows. 

Family  TIL  PHRAGMOTRICHACE^E. — Conceptacles  horny, 
breaking  through  epidermis  of  leaves,  etc.,  at  first  closed, 
then  bursting  longitudinally  ;  spores  septate,  and  in  chain- 
like  series,  with  paraphyses  on  internal  walls  of  concep- 
tacles. 

Gen.  1.  Endotrichvm. — Conceptacle  innate  or  immersed, 
bursting  by  a  longitudinal  slit ;  spores  globular,  simple. 

2.  Schizotkedum.  —  Conceptacle     superficial,    bursting 
laterally;  spores  globular,  simple. 

3.  Pilidium.  —  Conceptacles    simple,    sessile,    rounded, 
bursting  by  stellate  fission  ;  spores  spindle-shaped,  simple. 

4.  Exdpula.  —  Conceptacle    cup-shaped,    membranous, 
sessile,  naked  ;  spores  spindle-shaped. 

5.  Dinemasporium. — Conceptacle   cup-shaped,  membra- 
nous, sessile,  closed  by  villi,  and  at  length  open  ;  sporige- 
nous  layer  discoid,  dissolving,  with  cylindric,  elongate, 
filiform  spores. 

6.  Myxormia.  —  Conceptacle    thin,    cup-shaped,    open, 
formed  of  elongated  cells.     Pedicels  of  spores  delicate. 
Spores  oblong,  chained  together,  at  length  free,  involved 
in  mucus. 

7.  Cystotricha. — Conceptacle  bursting  by  a  longitudinal 
slit ;  pedicels  of  spores  branched,   articulate,  somewhat 
beaded. 

8.  Bloxamia. — Conceptacle  delicate,  hyaline,  upper  part 
evanescent  and  forming  a  rim.   Spores  quadrate  in  crowded 
tubules. 

9.  Phragmotrichum. — Conceptacle  horny,  carbonaceous, 
at   first   closed,  then    splitting  by  longitudinal   fissure ; 
fertile   filaments    mixed   with    inarticulate   paraphyses; 
spores  compound  and  chained  in  series. 


362  THE    MICROSCOPIST. 

Family  IV.  TORULACEI. — Mycelium  filamentous,  grow- 
ing on  the  surface  of  decayed  vegetables,  bearing  erect 
filaments,  terminating  in  rows  of  simple  or  compound 
spores. 

Gen.  1.  Torula. — Spores  in  beaded  chains,  simple,  readily 
separating,  placed  on  short  continuous  or  septate  pedicel. 

2.  Bixpora. — Spores  uniseptate. 

3.  Septonema. — Several  transverse  septa  in  the  spores. 

4.  Alternaria. — Cellular   spores  connected   by   filiform 
isthmus. 

5.  Sporidesmium. — Spores  in  tufts,  straight,  subclavate 
or  fusiform,  shortly  stalked  or  sessile,  transversely  sep- 
tate or  cellular. 

6.  Sporochisma. — Filaments  erect,  simple,  external  mem- 
brane inarticulate.    Spores  articulate  in  fours. 

7.  Tetraploa. — Spores  sessile,  quadriseptate,  in  bundles 
of  four,  each  crowned  with  a  bristle. 

8.  Coniothecium. — Spores  without  septa,  in  heaps,  finally- 
separating  into  a  powder. 

9.  Echinobotryum. — Spores  rounded  apiculate,  in  fasci- 
cles, or  erect  annulated  filaments. 

10.  Sporendonema. — Erect  filaments   with   single  rows 
of  spores  in  the  interior. 

11.  Spiloccea. — Spores  globose,  adhering  together  and  to 
the  matrix,  forming  spots  laid  bare  by  separation  of  epi- 
dermis. 

12.  Achorion. — Mycelium    ramose,    articulated,    joints 
terminating  in  round,  oval,  or  irregular  spores  (conidia?). 

13.  8peira. — Spores    connate   in    concentric   filaments, 
forming  horseshoe-like  lamina,  finally  separating. 

14.  Trimmatostroma. — Spores   curved,  multiseptate,  in 
beaded  rows,  separating. 

15.  Gyrocerus. — Spores  connate  in   spirally  coiled  fila- 
ments, separating. 

16.  Dictyosporium. — Spores    tongue-shaped,   reticularly 
cellular. 


APPENDIX.  363 

Family  V.  UREDINEI. — Mycelium  a  filamentous  mass 
growing  in  the  interior  of  living  vegetable  structures, 
finally  breaking  out  on  the  surface  in  patches,  margined  or 
naked,  and  bearing  simple  or  compound  spores,  single  or  in 
beaded  series. 

The  following  is  Tulasne's  synopsis  of  the  family  : 

I.  Albyginei  (white  or  pale-yellow,  heterosporous). 

Gen.  1.  Cystopus. 

II.  JEddinei  (with  a  peridium,  homcesporous). 

2.  Caeoma. 

3.  ^Ecidium. 

4.  Rsestelia. 

5.  Peridermium. 

III.  Melampsorei  (solid,  pulvinate,  biform). 

6.  Melampsora. 

7.  Coleosporium. 

IV.  Phragmidiacd  (pulverulent,  biform,  infuscate). 

8.  Phragmidium. 

9.  Triphragmidium. 

10.  Puccinia. 

11.  Uromyces. 

12.  Pileolaria. 

Y.  Pucdniei  (fleshy,  ligulate  or  tremelliform,  naked, 
and  uniform  in  the  fruits). 

13.  Podisoraa. 

14.  Gymnosporangium. 

VI.  Cronartiei  (peridiate,  biform,  ligulate). 

15.  Cronartium. 

Family  VI.  USTILAGINEI. — Similar  to  the  last,  but  grow 
in  the  interior  of  organs,  especially  ovaries  and  anthers, 
of  plants.  Spores  break  up  without  bursting  through  to 
surface,  so  as  to  leave  a  cavity  full  of  dustlike  spores. 

I.  Ustilagind  Veri. — Stroma  at  first  mucilaginous,  en- 
tire, or  soon  bro&en  up  into  variously  conglomerated 


364  THE    MICROSCOPIST. 

masses,  then  into  unappendaged  spores ;  few  or  no  fila- 
ments persistent. 

1.  Ustilago. — Spores  simple. 

2.  Thecaphora. — Spores  compound. 

II.  Tilletiei. — Stroma  of  interwoven  fragile  filaments ; 
spores  acrogenous  on  their  ramules,  often  appendaged 
when  free. 

3.  Tittetia. 

Order  HYPHOMYCETES.  — Mycelium  filamentous, 
growing  as  moulds  over  dead  or  living  organic  substances. 
The  erect  filaments  bear  terminal,  free,  single,  simple,  or 
septate  spores. 

Family  I.  ISARIACEI. — Receptacle  clavately  branched, 
of  filaments  attached  in  their  whole  length.  Spores  sim- 
ple, attached  to  simple  pedicels. 

Gen.  1.  Isaria. — Receptacle  of  interwoven  filaments, 
or  cellularly  fleshy.  Spores  on  simple  sporophores  arising 
on  all  sides. 

2.  Anthina. — Receptacle  of  parallel  filaments,  feathery 
or  villous  at  the  summit  where  they  form  the  sporo- 
phores. 

8.  Ceratium. —  Receptacle  horn-shaped,  mucilaginous, 
with  filaments  which  collapse  into  granules  (conidia),  and 
free  sporidia. 

Family  II.  STILBACEI. — Receptacle  wartlike  or  clavate 
above,  stalked  below,  of  filaments  packed,  coherent,  ter- 
minating singly  in  free  spores. 

Gen.  1.  Stilbum. — Receptacle  clavate  or  capitate  at  sum- 
mit. Spores  simple. 

2.  Pachnocybe. — Receptacle  stipitate,  clavate,   floccose, 
filaments    twisted,   head   finally   pruinose,   with    simple 
spores. 

3.  Periconia. — Receptacle  of  coalescent  crowded,  paral- 


APPENDIX.  365 

lei  filaments,  or  cellularly  fleshy  ;  spores  simple,  crowded, 
on  simple  sporophores  arising  at  summit  and  on  the 
stalk. 

4.  Tiibercularia. — Receptacle  fleshy,  of  continuous  sterile 
arid  threadlike  beaded  fertile  filaments.    Finally  indurated, 
floccose,  with   spores   scattered  over  it,  or  falling  into 
powder. 

5.  Periola. — Receptacle  cellular ,  sessile,  fertile  filaments 
abbreviated,  torulose,  mixed  with  septate  lax  sterile  fila- 
ments. 

6.  Volutella. — Receptacle  cellular,  compact,  with  long 
rigid  bristles  ;  spores  spindle-shaped,  septate,  on  continu- 
ous short  filaments,  all  over  the  receptacle. 

7.  Fusarium. — Receptacle  cellular,  gelatinous  ;   spores 
spindle-shaped,  simple,  somewhat  curved,  on  simple  fila- 
ments forming  a  discoid  stratum. 

8.  Illosporium. — Receptacle    sub-gelatinous,    diffluent  ; 
spores  simple,  pellucid,  generally  with  hyaline  envelope 
on  short  filaments. 

9.  Epicoccum. — Receptacle  cellular,  on   effused  patch  ; 
spores  four-sided,  cellular,  singly  to  short  filaments. 

Family  III.  DEMATIEI. — Mycelium  filamentous,  spores 
compound  or  simple,  rising  from  apices  of  erect,  solid,  cor- 
ticate, subopaque  filaments,  or  produced  from  solution  of 
the  plants. 

Gen.  1.  Cephalotrichum.  —  Fertile  filaments  stalklike, 
erect,  septate,  terminating  in  a  globose  capitule  formed 
by  radiating  forked  or  ternate  branches  bearing  globular 
spores  at  the  tips. 

2.  Sporocybe. — Filaments    fibrous,   subulate,   capitate, 
with  simple  spores  conglobated  into  a  terminal  head. 

3.  (Edemium. — Filaments  rigid,  erect,  almost  continu- 
ous, or  annulated,  bearing  at  the  sides  globular  masses  of 
spores. 

4.  Myxotrichum. — Filaments    erect,   scarcely   septate  ; 


366  THE    MICROSCOPIST. 

fertile  branches  crowned  by  globules  of  heterogeneous  eon- 
glutinated  spores. 

5.  Bolacotricha. — Filaments  simple,  uniformly  articulate 
at   apex;   spores   conglomerate,   large,   globular,  shortly 
stalked,  contents  granular. 

6.  Helminthosporium. — Filaments  erect,  simple,  septate  ; 
spores  transversely  septate. 

7.  Triposporium.  —  Filaments     erect,    septate,    sterile 
branches  solitary,  more  or  less  spreading  ;  fertile  branches 
shorter,  at  tips  solitary,  stellate,  shortly  stalked  spores. 

8.  Helicosporium. — Filaments  subulate,  closely  septate, 
diaphanous  at  summit ;  spores  threadlike,  septate,  spirally 
coiled,  then  expanding  elastically. 

9.  Cladotrichum. — Filaments  septate,  branched,  branches 
and  branchlets  with  septate  spores  at  tips. 

10.  Dematium. — Filaments    septate,    with    verticillate 
branchlets   below,   simple    and   whiplike   above ;   spores 
crowded  on  apices  of  ramules. 

11.  Cladosporium. — Filaments   septate   above,  bearing 
spores  in  rows  forming  short  moniliform  branchlets. 

12.  Macrosporium. — Filaments   suberect,  septate,   deli- 
cate, evanescent,  with  erect  stipitate  spores,  with  many 
transverse  and  usually  some  longitudinal  septa. 

13.  Arthrineum. — Filaments  tufted,  suberect,  annulate 
with  opaque  septa  ;  spores  fusiform,  septate,  large. 

14.  Camptoum. — Filaments  as  preceding ;  spores  ovate, 
curved,  small. 

Family  IV.  MUCIDINES. — Mycelium  filamentous,  spores 
solitary,  or  crowded  on  articulated  or  branched  tubular 
and  pellucid  filaments,  soon  separating  and  mingling  with 
the  mycelium  or  adherent  in  chained  rows  (moulds,  mil- 
dews, etc.). 

A.  Fertile  filaments  (pedicels)  simple  or  branched,  ter- 
minating in  single  spores,  or  a  short  row. 

*  Spores  simple. 


APPENDIX.  367 

1.  Botrytis. — Pedicels  erect,  septate,  branched  ;  branches 
and  branchlets  septate ;  spores  solitary,  on  tips  of  branch- 
lets,  which  are  racemose,  umbellate,  cymose,  etc. 

2.  Peronospora. — Like  1,  but  pedicels  without  septa. 

3.  Verticillium. — Pedicels  erect,  septate,  with  whorled 
branches  terminating  in  a  solitary  spore  or  a  short  row  of 
spores. 

4.  Acremomum. — Pedicels  short,  subulate,  branches  from 
a  horizontal  filament,  bearing  single  smooth  spores. 

5.  Zygodesmus. — Like  4,  but  with  echinulate  spores. 

6.  Oidium. — Pedicels  simple,  short,  erect,  clavate,  sep- 
tate, with  one,  sometimes  two,  oval  spores. 

7.  Pasidium. — Spores  elongate,  fusiform. 

8.  Menispora. — Pedicels   erect,  septate,  with   fusiform 
or  cylindric  spores,  at  first  joined  in  bundles. 

9.  Sceptromyces. — Pedicels    erect,    geniculate,    verticil- 
lately   branched ;   branches   short,   racemose ;    spores   in 
grapelike  bunches. 

*  *  Spores  septate. 

10.  Brachydadium. — Pedicels  branched  above,  septate, 
moniliform ;  branches  and  branchlets  forming  a  sporifer- 
ous  capital  urn  ;  spores  transversely  septate. 

11.  Trichothedum. — Pedicels  in  tufts,  the  central  erect, 
fertile ;  spores    acrogenous,    didymous,    free,   commonly 
loosely  heaped. 

12.  Cephalothecium. — Pedicels  simple,  continuous,  with 
terminal  head  of  didymous  spores. 

B.  Erect  filaments  (pedicels)  terminating  in  strings  of 
spores. 

*  Spores  simple. 

13.  Penicillium. — Pedicels   erect,   septate,   penicillately 
branched  above  ;  branches  and  branchlets  septate  ;  strings 
of  spores  at  tips  of  branches. 

14.  Sporotrichum. — Pedicels  simple  or  slightly  branched, 
septate    and    articulate,   articulations   remote,   inflated ; 
spores  simple,  usually  in  heaps  among  the  filaments. 


368  THE    MICROSCOPIST. 

15.  Briarea. — Pedicels  septate,  with  terminal  monili- 
form  chains  of  spores,  crowded  into  a  head, 

16.  Gonatorrhodum. — Pedicels  septate,  with   chains  of 
spores  in  a  terminal  head,  and  in  whorls  at  the  joints. 

*  *  Spores  septate. 

17.  Dendryphium. —  Pedicels      septate,      unbranched  ; 
strings  of  spores  in  a  bunch  at  apex ;  spores  septate. 

18.  Dactylium. — Pedicels    septate,    branched     above; 
strings  of  septate  spores  singly  or  in  pairs,  at  apices  of 
branches. 

C.  Fertile  filaments  (pedicels)  inflated  at  the  tips  or  at 
various  points  in  their  length,  with  projecting  points  or 
warts,  on  the  inflations  bearing 

*  Simple  spores. 

19.  Aspergillus. — Pedicels  continuous,  erect,  simple  fila- 
ments, inflated  into  a  little  head  at  the  summit,  bearing 
moniliform  chains  of  spores,  crowded  into  a  capitulum. 

20.  Rhinotrichum. — Pedicels   erect,   septate,  sometimes 
sparingly  branched,  the  apices  clavate,  cellular,  bearing 
scattered  points  supporting  simple  spores. 

21.  Papuloespora. — Pedicels  short  lateral  branches  from 
a  creeping  filament,  terminating  in  cellular  heads  beset 
with  spores  on  the  areolae. 

22.  Rhopalomyces. — Pedicels  erect,  not   septate,  termi- 
nating in  cellular  heads,  with  simple  spores  on  the  areolre. 

23.  Stachylidium. — Pedicels  articulate,  whorled-branched 
above ;  branches  geniculate   and  articulate  ;   spores  sub- 
pedicilate,  in  little  heads  inserted  at  tips  of  branches. 

24.  Gonatobotrys. — Pedicels  septate,  with  joints  swollen 
at  intervals,  the  swollen  joints  bearing  globular  heaps  of 
spores  on  short  spines  spirally  arranged. 

25.  Acmosporium. — Pedicels   septate,  branched   above ; 
branches  and  branchlets  forming  a  cyme,  thickened  at  the 
apex,  and  furnished  with  globular  capitules  covered  with 
points  ;  spores  attached  on  the  points  of  capitules. 


APPENDIX.  369 

26.  Haplotrichum. — Pedicles  septate,  terminating  in  con- 
tinuous, solitary,  sporiferous  head. 

27.  Actinodadium.  —  Pedicles       septate,     umbellately 
branched   at    summit ;    spores    accumulated   at   tips   of 
branches. 

28.  Botryiosporium. — Pedicles  septate,  with  short  spine- 
like  branchlets  above,  spirally  arranged,  and  terminating 
in  four  or  five  short  points  which  support  globular  heads 
of  spores. 

*  *  Spores  septate. 

29.  Arthrobotrys. — Pedicles  simple,  septate,  with  joints 
swollen  at  intervals  and  clothed  with  spines  bearing  didy- 
mous  spores  in  globular  heaps. 

5.  Family  Sepedoniei.— Mycelium  filamentous,  spores 
usually  heaped  together  on  the  mycelium,  and  apparently 
springing  out  of  it,  without  erect  pedicles. 

1.  Artotrogus. — Filaments   creeping,  persistent;   spores 
from  middle  of  filaments,  simple,  at  length  free,  spinous. 

2.  Sepedonium. — Filaments  woolly, septate,  evanescent; 
spores   globose,  connate,  scabrous,   stipitate,  solitary,  at 
length  heaped  together. 

3.  Fussisporium. — Spores  fusiform  or  cylindrical,  glued 
in  heaps  on  the  gelatinous  matrix. 

4.  Epoehnium. — Spores  heaped,  oblong,  apiculate,  sep- 
tate,  adnate   to   the   matrix,   interwoven   with   effused, 
tangled,  slender  filaments  of  mycelium. 

5.  Psilonia. — Spores  simple,  pellucid,  not  glued  together, 
at  first  covered  with  conveying  filaments  of  mycelium. 

6.  Monotospora — Eutophyte. — Filaments  creeping,  evan- 
escent ;  spores  globose,  solitary,  terminal,  at  length  free. 

7.  Asterophora. — Filaments  creeping  (over  larger  fungi) ; 
spores  on  short  ramules,  vesicular,  stellate. 

8.  Acrospeira. — Filaments  creeping,  ramuli    branched, 
the  fertile  terminating  in   a  spiral  coil  of   about  three 
joints,  one  of  which  swells  into  a  rough-coated  spore. 

24 


370  THE    MICROSCOPIST. 

9.  Zygodesmus. — Filaments  creeping,  branched,  with 
short  rarnuli  bearing  echinate  spores,  the  pedicles  with  a 
lateral  indentation  looking  like  a  joint. 

Order  PHYSOMYCETES,  or  Mucoroidece  (Moulds).— 
Mycelium  (microscopic)  filamentous,  bearing  stalked  sacs 
(peridiola)  containing  numerous  minute  sporules. 

Family  I.  ANTENNARIEI  (doubtful). — Mycelium  radiate 
or  erect,  bearing  sessile  globular  peridioles,  filled  with 
ovate  spores,  discharged  by  rupture  of  sac  at  apex.  Form 
flocculent  or  byssoid  patches  on  leaves  or  bark,  and  appear 
to  be  merely  states  of  other  genera. 

Family  II.  MUCORINI. — Mycelium  filamentous,  vague, 
giving  off  erect  simple  or  branched  filaments  terminating 
in  vesicular  cells  (peridioles)  full  of  minute  spores ;  often 
with  central  column  in  the  interior.  Form  flocks  and 
clouds  on  decaying  matters- 

1.  Phycomyces. — Peridiole  pear-shaped,  separated  from 
apex  of  pedicle  by  an  even  joint ;  opening  by  an  umbili- 
cus.    Spores  oblong,  large.     Filaments  tubular,  continu- 
ous, shining. 

2.  Hydrophora. — Peridiole  subglobose,  membranous,  de- 
hiscent, at  first  crystalline,  aqueous,  then  turbid,  and  at 
length  indurated;  bolumella  absent;  spores  simple,  con- 
globated. 

3.  Mucor. — Peridiole  subglobose,  separating  like  a  cap 
(an  annular  fragment  attached),  from  the  erect,  simple 
pedicle,  or  bursting  irregularly;   columella  cylindric  or 
ovate,  spores  simple. 

4.  Acrostalagmus  (?). — Peridioles  globose,  with  a  colu- 
mella; at  the  points  of  doubly- verticillate  branches  from 
an  erect  pedicle. 

5.  JEgerita. — Peridiole  spherical,  very  fugacious  ;  spori- 
dia  scattered  like  meal  over  the  grumous  receptacle. 


APPENDIX.  371 

6.  Pilobolus. — Peridiole  globular,  separating  like  a  cap 
from  the  short  stalk  of  a  single  cell,  attached  on  a  uni- 
cellular  ramified   mycelium  ;   columella   conical  ;   spores 
numerous,  free  in  the  peridiole. 

7.  Syzygit.es. — Filaments  erect,  simple,  branched  above, 
branches    and   branchlets    di-   or    tri-chotomous,   fertile 
branches  forcipate,  bearing  pairs  of  opposite  internal  cla- 
vate  branches  which  subsequently  coalesce. 

8.  Eurotium. — Peridiole  cellular,  membranous,  sessile, 
at  length  bursting  irregularly  ;  spores  produced  by  a  cen- 
tral cellular  nucleus,  which  breaks  up  into  numerous  pa- 
rent cells  (asci),  in  which  four  to  eight  minute  spores  are 
formed,  and  finally  set  free  ;  filaments  of  mycelium  ra- 
diating from  the  base  of  the  peridiole. 

ALG^E— SEAWEEDS,  ETC. 

Order  I.  RHODOSPERMEJE  or  FLORIDE^E  —  Thal- 
lus  leaflike  or  filamentous,  rose-red  or  purple.  Fructifi- 
cation consisting  of:  1.  Spores,  mostly  inclosed  in  concep- 
tacles  (ceramidia,  coccidia,  favellidia,  etc.).  2.  Tetraspores, 
red  or  purple  (a  membranous  sac  containing,  when  ripe, 
four  spores).  3.  Antheridia  (pellucid  sacs  filled  with 
yellow  corpuscles  or  spermatozoids). 

Families  I.  RHODOMELACEJE. — Frond  cellular,  areolated 
or  articulated.  Ceramidia  external.  Tetrapores  in  rows, 
immersed  in  ramuli  or  contained  in  proper  receptacles 
(stichidia). 

1.  Odonthalia. — Frond  flattened,  linear,  with   obsolete 
midrib,  pinnatifid,  alternately  inciso-dentate. 

0.  dentata. — Color,  wine-red. 

2.  Ehodomela. — Frond  cylindric,  inarticulate,  opaque. 
Tetraspores  in  podlike  receptacles  (stichidia). 

R.  lycopodioides. — Purplish-brown. 
R.  subfusca. — Brownish  or  reddish. 

3.  Bostrychia. — Frond    cylindric,   inarticulate,   dotted. 
The  surface-cells  quadrate.     Tetraspores  in  terminal  pods. 


372  THE    MICKOSCOPIST. 

4    4.   RytiphlcBa. —  Frond    cylindric,    inarticulate,    trans- 
versely striate.     Tetraspores  in  podlike  receptacles. 

5.  Polysiphonia. — Frond  cylindric,  articulate  in  whole 
or  in  part,  the  branches  longitudinally  striate.    Tetraspores 
in  distorted  ramuli. 

6.  Dasya. — Frond  cylindric,  the  stem  inarticulate,  ra- 
muli articulate,  composed  of  a  single  string  of  cells.     Te- 
traspores in  podlike  receptacles  (stichidia)  borne  by  the 
ramuli. 

2.  LAURENCIACE^. — Frond  cellular,  continuous.  Cera- 
midia external.  Tetraspores  scattered,  immersed  in  the 
branches  and  ramuli. 

1.  Bonnemaisonia. —  Frond     solid,    filiform,    rose-red. 
Much  branched  ;  branches  margined  with  subulate  dis- 
tichous cilia. 

2.  Laurenda. — Frond   solid,  cylindric,   or   compressed 
(purple  or  yellowish),  pinnatifid.     The  ramuli  blunt. 

3.  Chrysimenia. — Frond    hollow,   filled    with    mucus, 
neither  constricted  nor  chambered. 

4.  Chylodadia. — Branches  hollow,   filled  with    mucus, 
constricted  at  intervals  and  chambered. 


3.   CORALLINACE^E. — Frond  calcareous   or  crustaceous, 
rigid.     Ceramidia  external,  containing  the  tetraspores. 

*  Frond  filiform,  articulate. 

1.  Corallina. — Frond  pinnated.      Ceramidia   terminal, 
simple. 

2.  Jania. — Frond  dichotomous.     Ceramidia  tipped  with 
two  hornlike  ramuli. 

*  *  Frond  crustaeeous  or  foliaceous,  opaque,  not  articu- 
late. 

3.  Melobesid. — Frond  stony,  forming  a  crustaceous  ex- 
pansion, or  a  foliaceous  or  shrublike  body. 

4.  Hildebmndtia. — Frond  cartilaginous,  not  stony. 


APPENDIX.  373 

*  *  *  Frond  plain,  hyaline,  composed  of  cells  radiat- 
ing from  a  centre.     Fructification  unknown. 

5.  Lithocystis  (a  minute  parasite). — L.  allmanni  forms 
minute  white  dots  on  Chrysimenia  davelosa,  consisting  of 
fanshaped  fronds  composed  of  square  cells. 

4.  DELESSERICE^. — Frond  cellular,  continuous,  areolated. 
Coccidia    external.      Tctraspores    collected    into    definite 
clusters  (sori). 

1.  Delesseria.- — Frond  leafy,  of  definite  form,  with  per- 
current  midrib. 

2.  Nitophyllum. — Frond  leafy,  of  indefinite  form.     No 
midrib  (sometimes  vague  nerves). 

3.  Plocamium. — Frond  linear   or   filiform,  compressed. 
Much  branched,  distichous,  ramuli  pectinate,  secund. 

5.  RHODYMENIACE^:. — Frond   cellular,   continuous  ;  the 
superficial  cells  minute.     Coccidia  external.     Tetraspores 
scattered  through  the  frond  or  forming  undefined,  cloud- 
like  patches. 

*  Frond  flat,  expanded,  leaflike,  dichotomous  or  pal- 
mate. 

1.  Stenogramme. — Conceptacles  linear,  riblike. 

2.  Hhodymenia. — Conceptacles  hemispherical,  scattered. 

*  *  Frond  compressed  or  terete,  linear  or  filiform,  much 
branched. 

3.  Sphcerococcus. — Frond  linear,  compressed,  two-edged, 
distichously  branched,  with  obscure  midrib. 

4.  Gracilaria. — Frond  filiform,  compressed  or   flat,  ir- 
regularly branched  ;  the  central  cells  very  large. 

5.  Jdypnea. — Frond     filiform,     irregularly    branched, 
traversed  by  a  fibro-cellular  axis. 

6.  CRYPTONEMIACE.E. — Frond  fibro-cellular,  composed  of 
articulated  fibres   connected  by   gelatin.     Favellidia  im- 
mersed in  the  frond  or  sub-external.    Tetraspores  immersed 
in  the  frond. 


374  THE    MICROSCOPIST. 

1.  Sub-tribe  COCCOARPEJE. — Frond  solid,  dense,  cartilagi- 
nous, or  horny.  Favellidia  in  semi-external  tubercles  or 
swellings  of  frond. 

1.  Grateloupia. — Frond  pinnate,   flat,  narrow,    dense, 
membrano-cartilaginous.      Favellidia    immersed    in    the 
branches,  communicating   with   the   surface  by  a  pore. 
Tetraspores  scattered. 

2.  Gelidium.  —  Frond    pinnate,    compressed,    narrow, 
horny.     Favellidia  immersed  in   swollen   ramuli.     Tetra- 
spores forming  subdefined  sori  in  the  ramuli. 

3.  Gigartina. — Frond  cartilaginous,  cylindric,  or  com- 
pressed,  its  flesh    composed  of  anastomosing   filaments 
lying  apart  in  firm  gelatin.     Favellidia  in  external  tuber- 
cles.    Tetraspores  in  dense  sori  sunk  in  the  frond. 

2.  Sub-tribe  SPONGIOCARPEJE. 

4.  Chondrus. — Frond   fan-shaped,  dichotomously  cleft, 
cartilaginous,  dense.     Tetraspores  in  sori  immersed  in  sub- 
stance of  frond. 

5.  Phyllophora. — Frond  stalked,  rigid,  membranaceous, 
proliferous  from  the  disk,  dense.     Tetraspores  in  distinct 
superficial  sori  or  in  special  leafletlike  lobes. 

6.  Peyssonelia. — Frond  depressed,  expanded,  rooting  by 
the  under  surface,  concentrically  zoned,  membranous  or 
leathery.     Tetraspores  in  superficial  warts. 

7.  Gymnogongrus. — ^rondfiliform,dichotomous,  horny, 
of  dense  structure.    Tetraspores  strung  together,  contained 
in  superficial  wartlike  sori. 

8.  Polyides. — Root  scutate.     Frond  cylindric,  dichoto- 
mous,  cartilaginous.     Favellce.  in  spongy  external  warts. 
Tetraspores  scattered  in  peripheric  stratum  of  frond,  cru- 
ciate. 

9.  Furcellaria. — Root  branching.     Frond  cylindric,  di- 
chotomous,  cartilaginous.   Favellce  unknown.     Tetraspores 
imbedded  among  filaments  of  periphery,  in  swollen  pod- 
like  upper  branches  of  frond,  transversely  zoned. 

3.  Sub-tribe  GASTROCARPE^I. — Frond  gelatinously  mem- 


APPENDIX.  375 

branous  or  fleshy,  often  of  lax  structure  internally.   Pavel- 
lidia  immersed  in  central  substance  of  frond,  very  numerous. 

10.  Dumontia. — Frond  cylindric,  tubular,  membranous. 
Tufts  of  spores  attached  to  wall  of  tube  inside. 

11.  Halymenia. — Frond  compressed   or   flat,   gelatino- 
membranaceous,  surfaces  separated  by  a  few  slender  anas- 
tomosing filaments.     Masses  of  spores  attached  to  inner 
face  of  membranous  wall. 

12.  Ginannia. — Frond  cylindric,  dichotomous,  traversed 
by  a  fibrous  axis,  walls  membranous.     Masses  of  spores 
on  inner  face  of  wall. 

13.  Kallymenia. — Frond  expanded,  leaflike,  fleshy-mem- 
branous, solid,  dense.     Favellidia  like  pimples,  half  im- 
mersed and  scattered. 

14.  Iridea. — Frond    expanded,   leaflike,  thick,   fleshy- 
leathery,  solid,  dense.   Favellidia  wholly  immersed,  densely 
crowded. 

15.  Catanella. — Frond  filiform,  branched,  constricted  at 
intervals  into  oblong  articulations ;  the  tube  filled  with 
lax  filaments. 

4.  Sub-tribe  GLOIOCLADIE^E. — Frond  loosely  gelatinous, 
the  filaments  lying  apart,  surrounded  by  a  copious  gela- 
tin. Favellidia  immersed  among  filaments  of  periphery. 

16.  Cruoria. — Frond  crustaceous,  skinlike. 

17.  Naccaria. — Frond  filiform,  solid,  cellular;   ramuli 
only  composed  of  radiating  free  filaments. 

18.  Gloiosiphonia. — Frond  tubular,  hollow,  walls  com- 
posed of  radiating  filaments. 

19.  Nemaleon. — Frond  filiform,  solid,  elastic,  filament- 
ous, axis  of  a  network  of  anastomosing  filaments ;  periph- 
ery of  moniliform  free  filaments. 

20.  Dudresnaia. — Frond  filiform,  solid,  gelatinous,  fila- 
mentous, axis  and  periphery  like  the  last. 

21.  Cronania. — Frond  filiform,  of  a  jointed   filament, 
whorled  at  the  joints,  with  minute  multifid,  gelatinous 
ramuli. 


376  THE    MICROSCOPIST. 

7.  CBRAMIACE^I. — Frond  filiform,  of  an  articulated  fila- 
ment, simple,  or  coated  with  stratum  of  small  ceils.  Fa- 
vellce naked,  berrylike  masses.  Tetraspores  external  or 
partially  immersed. 

1.  Ptilota. — Frond  compressed,  inarticulate,  distichous, 
pectinato-pinnate.     Favellce  pedunculate,  involucrate. 

2.  Microcladia. — Frond  filiform,  inarticulate,   dichoto- 
mous.     Favellce  sessile,  involucrate. 

3.  Ceramium. — Frond  filiform,  articulate,  dichotomous ; 
the  joints  opaque.      Favellce  sessile,  mostly  involucrate. 
Tetraspores  mostly  immersed. 

4.  Spyridia. — Frond  filiform,  inarticulate ;  the  branches 
clothed  with  minute,  setiform,  articulate  ramelli.   Favellce 
pedunculate,  involucrate.     Tetraspores  sessile  on  the  ra- 
melli. 

5.  Griffithsia. —  Frond    articulated,    dichotomous,    or 
clothed   with    whorled,    dichotomous   ramelli,    rose-red. 
Favellce  involucrate,  sessile,  or  pedunculate.     Tetraspores 
sessile,  or  whorled  ramelli. 

6.  Wrangelia. — Frond  articulated,   pinnate.      Favellce 
terminal,  involucrate  with   tufts  of  pear-shaped  spores. 
Tetraspores  sessile,  scattered  on  the  ramelli. 

7.  Seirospora. — Frond  articulated.    Tetraspores  arranged 
in  terminal  moniliform  strings. 

8.  Callithamnion. — Frond,  at  least  the  branches  and  ra- 
muli,  articulate,  mostly  pinnated.     Favellce  terminal  or 
lateral,  sessile  without  involucre  (except  in  C.  turneri). 
Tetraspores  sessile  or  pedicellate,  scattered. 

9.  Trentepohlia. —  Frond  articulate,  branched,  cells   in 
single  series.     Favellce  ?  in  terminal  corymbs. 

8.  PORPHYRACEJE. — Frond  plain  and  very  thin,  or  tubu- 
lar and  filiform,  purplish,  with  oval  spores  in  sori  and 
tetraspores  scattered  over  the  frond. 

1.   Porphyra. — Frond  plain,   membranous,   very   thin, 


APPENDIX.  377 

purple  ;  oval  spores  in  sori,  and  tetraspores  (square)  scat- 
tered over  frond. 

2.  Bangia. — Frond  filiform,  tubular,  composed  of  radiat- 
ing cells  in  transverse  rows,  in  continuous  hyaline  sheath. 

Order  II.  MELANOSPORE^E  or  FUCOIDEJE.— Ma- 
rine. Thallus  leaflike,  or  cordlike,  or  filamentous.  Olive- 
green  or  brown.  Fructification  varied.  1.  In  Fucaceee,  mo- 
noecious or  dioecious  conceptacles  containing  sporanges  and 
antheridia;  the  spores  being  fertilized  by  spermatozoids 
after  discharge  of  both  from  the  parent.  2.  In  Lamina- 
riacese,  etc.,  of  collections  of  clavate  or  filiform  sporanges 
producing  zoospores,  with  antheridia-like  Fucacese.  3.  In 
Cutleriacese  similar.  4.  In  Dictyotacese  three  forms  re- 
sembling Floridese ;  tetraspores,  sporanges  containing  sim- 
ple spores,  and  antheridia. 

Family  I.  FUCACEJE. — Frond  leathery  or  membranous, 
cellular.  Spores  and  antheridia  together  or  separate  in 
spherical  cavities  imbedded  in  the  frond. 

*  Air-vessels  stalked. 

1.  Sarpassum. —  Branches  bearing  ribbed  leaves;  air- 
vessels  simple. 

2.  Halidrys. — Frond  linear,  pinnate,  leafless  ;    air-ves- 
sels divided  by  transverse  partitions. 

*  *  Air-vessels   immersed   in   substance   of  frond,   or 
absent. 

3.  Cytoseira. — Root    scutate.      Frond   much  branched, 
bushy.     Receptacles  cellular. 

4.  Pycnophycus. — Root  branching,   Frond  cy  \mdr\Q.  Re- 
ceptacles cellular. 

5.  Fucus. — Root  scutate.     Frond  dichotomous.     Recep- 
tacles filled  with  mucus,  traversed  by  jointed  threads. 

6.  Himanthalia. — Root  scutate.   Frond  cup-shaped.   Re- 
ceptacles   (frondlike)    long,   strap-shaped,   dichoraotously 
branched. 


378  THE    MICROSCOPIST. 

3.  DICTYOTACEJE. — Frond  cellular,  flat,  compact.  Spores, 
antheridia  (and  tetraspores  T)  in  spots  or  lines  (sori)  on  sur- 
face. 

1.  Haliseris. — Frond  dichotomous  with  midrib. 

2.  Padina. — Frond   ribless,  fan-shaped,  concentrically 
streaked.     Sori  linear,  concentric,  bursting  through  the 
epiderm. 

3.  Zonaria. — Frond  ribless,  lobed,  concentrically  striate. 
Sori  roundish,  with  spores  and  jointed  threads. 

4.  Taonia. — Frond  ribless, 'cleft  irregularly,  somewhat 
fan-shaped.   Sori  linear,  concentric,  superficial,  alternating 
with  scattered  spores. 

5.  Dictyota. — Frond  ribless^  dichotomous.     Sori  round- 
ish, scattered,  bursting  through  epiderm,  or  (on  distinct 
individuals)  scattered  spores. 

3.  CUTLERIACEJL — Frond    cellular,    compact,    ribless. 
Dotlike  collections  of  sporanges  divided  into  eight  com- 
partments, and  antheridia  (?)  consisting  of  chambered  fila- 
ments in  groups  of  curved  jointed  hairs. 

1.  Cutleria. 

4.  LAMINARIACE^:. — Frond  leathery  or  gelatinous,  cellu- 
lar.    Unilocidar  sporanges  in  cloudlike  patches,  or  cover- 
ing the  whole  surface  of  frond ;  or  multilocular  sporanges 
clothing  the  whole  surface  of  the  frond  like  an  epidermis. 

*  Frond  stalked,  the  stalk  ending  in  an  expanded  leaf- 
like  portion. 

1.  Alaria. — Leaf  membranous,  with  cartilaginous  per- 
current  midrib. 

2.  Laminaria. — Leaf  (simple   or    cleft)   without    any 
midrib. 

*  *  Frond  simple,  leafless. 

3.  Chorda.— Frond  cylindric,  hollow,  the  cavity  having 
transverse  partitions. 


APPENDIX.  379 

5.  DICHTYOSIPHONACE.E. — Frond    cylindric,    branched, 
filamentous    in    structure.      Ovoid    sporanges  imbedded 
lengthwise  in  substance  of  frond,  opening  by  a  pore  on 
the  surface. 

1.  Dictyosiphon. — Root  a  minute   naked   disk.     Frond 
cylindric,  branched.      Oosporanges   irregularly  scattered, 
solitary  or  in  dotlike  sori. 

2.  Striaria  Oosporanges  in  transverse  lines  on  surface  of 
frond. 

6.  PUNCTARIACEJE. — Frond  cylindric  or  flat,  unbranched, 
cellular.     Ovate  sporanges  in  groups  on  the  surface,  inter- 
mixed with  clavate  filaments  (paraphyses}. 

1.  Punctaria. — Frond  flat  and  leaflike.     Sporanges  scat- 
tered or  in  sori. 

2.  Asperococcus. — Frond    membranous,   tubular,   cylin- 
dric, or  compressed.     Sporanges  in  dotlike  sori. 

3.  Litosiphon. — Frond  cartilaginous,  filiform,  subsolid. 
Sporanges  scattered,  almost  solitary. 

7.  SPOROCHNACE.E. — Frond    leathery   or    membranous, 
cellular,  branched.     Unilocular  or  multilocur  sporanges  at- 
tached to  external  jointed  filaments,  free  or  collected  in 
knoblike  masses. 

*  Sporanges  on  pencilled   filaments  issuing   from   the 
branches  (Arthrocladiese). 

1.  Demarestia. — Frond    solid   or    flat,    dichotomously 
branched. 

2.  Arlhrocladia. — Frond  traversed  by  a  jointed  tube, 
filiform,  nodose. 

3.  Stilophora. — Frond  filiform,  tubular  or  solid,  branched. 
Sporanges   from   necklace-shaped   filaments   in   wartlike 
groups  on  the  frond. 

*  *•  Sporanges   in  knoblike    receptacles    composed   of 
whorled  filaments  (Sporochnese). 

4.  Sporochnus. — Receptacles  lateral  on  short  peduncles. 


380  THE    MICROSCOPIST. 

5.   Carpomitra. — Receptacles    terminal,  at    tips   of    the 
branches. 

8.  CHORDARIACE.E. — Frond  cartilaginous  or  gelatinous, 
of  horizontal  and  vertical  filaments  (jointed)  interlaced. 
Unilocular  sporanges  from  the  base  of  the  vertical  fila- 
ments forming  the  epiderm  of  the  frond,  and  multilocular 
sporanges  developed  later  from  filaments  surrounding  the 
former. 

1.  Chordaria. — Axis  cartilaginous,   dense,  filaments  of 
circumference  unbranched. 

2.  Mesogloia. — Axis  gelatinous,  loose,  filaments  of  cir- 
cumference branching. 

9.  MYRIONEMACE.E. — Frond    tubelike,  crustaceous    or 
spreading  as  a  crust,  of  filamentous  structure.     Unilocu- 
lar and  multilocular  sporanges  attached  to  the  superficial 
filaments  and  concealed  among  them. 

1.  Leathesia. — Frond  tuber-shaped. 

2.  Ralfsia. — Frond  crustaceous. 

3.  Elachistea.     Frond  parasitic,  of  a  tubular  base,  bear- 
ing pencilled  erect  filaments. 

4.  Myrionema. — Frond  parasitic,  forming  a  flat   base, 
bearing  cushionlike  tufts  of  decumbent  filaments. 

10.  ECTOCARPACE^I. — Frond  filiform,  jointed.     Unilocu- 
lar sporanges,  ovate  sacs  at  ends  or  intermediate  joints  of 
the  filaments  and  multilocular  sporanges  of  minute  jointed 
filaments  in  similar  situations.   Antheridia  with  spermato- 
zoids  in  Sphacelaria. 

*  Frond   rigid,  each   articulation   of    numerous    cells 
(Sphacelariece). 

1.  Cladostephus. — Ramuli  whorl ed. 

2.  Sphacelaria. — Ramuli  distichous,  primated. 

*  *  Frond  flaccid,  each  articulation  of  a  single  cell. 

3.  Ectocarpus. — Frond  branching,  ramuli  scattered. 


APPENDIX.  381 

4.  Myriotrichia. — Frond  unbranched,  ramuli  whorled, 
tipped  with  pellucid  fibres. 

Order  III.  CHLOROSPOKE^E  or  CONFERVOIDE^E. 
— In  sea  or  fresh  water,  or  on  damp  surfaces,  with  fila- 
mentous, or  more  rarely  a  leaflike  thallus;  microscopic 
forms,  sometimes  pulverulent  or  gelatinous,  consisting  fre- 
quently of  definitely  arranged  groups  of  distinct  cells, 
with  an  ordinary  structure,  or  with  their  membrane  silici- 
fied  (Diatomacese).  Fructification  varied. 

1.  Resting  spores  produced  from  cell-contents  after  fer- 
tilization either  by  conjugation  or  impregnation. 

2.  Spermatozoids  produced  from  the  contents  of  other 
cells. 

3.  Zoospores. — Two,  four  or  multiciliated  active  gonidia, 
discharged  from  the  vegetative  cells  without  impregna- 
tion and  germinating  directly. 

The  simple  vegetative  increase  of  unicellular  forms  is 
analogous  to  cell  division  of  filamentous  forms. 

The  Yolvocinese  pass  the  vegetative  stage  of  existence 
as  ciliated  zoospores  collected  within  a  gelatinous  com- 
mon envelope. 

Family  I.  LEMANEJE. — Frond  cartilaginous,  leathery, 
inarticulate,  filamentous,  hollow,  with  whorls  of  warts 
at  irregular  distances,  or  necklace-shaped.  Fructification 
tufted,  simple,  or  branched  ;  necklace-shaped  filaments,  at- 
tached to  inner  surface  of  tubular  frond,  and  breaking  up 
into  elliptic  spores.  Grow*  in  fresh  water. 

1.  Lemania. — Two  species,  L.  torulosa  and  L.fluwatilis, 
in  clear  running  streams. 

2.  BATRACHOSPERMEJE. — Plants  filamentous,  articulated, 
invested  with  gelatin.     Frond  of  aggregated,  articulate, 
longitudinal  cells,  whorled  at  intervals,  with  short,  hori- 
zontal, cylindric,  or  beaded,  jointed  ramuli.    Fructification 


382  THE    MICROSCOPIST. 

ovate  spores,  and  tufts  of  antheridial  cells  (?)  attached  to 
the  lateral  ramuli,  which  consist  of  minute,  radiating, 
dichotomous,  beaded  filaments.  Fresh-water  plants. 

1.  Batrachospermum. — Lateral  whorled  ramuli,  beaded 
spores  in  globular  knobs  in  the  whorls. 

1.  B.  moniliform. — Color  various,  vaguely  branched. 

2.  B.  giganteum. — Large,  purple  when  dry,  long,  bifur- 
cated branches. 

3.  B.  affine. 

4.  B.    coerulescens. — ^Eruginous,     slender,    branched. 
Upper  and  lower  whorls  confluent. 

5.  B.  vagum. — Dichotomously  branched,  equally  thick 
throughout ;  whorls  all  confluent. 

2.  Thorea. — Stems    continuous,    whorled,    articulated, 
sometimes  branched,  ramuli  cylindric,  the  spores  at  their 


3.  CH^ETOPHORACE^:. — In  the  sea  or  fresh  water,  coated 
by  gelatinous  substance,  either  filiform  or  (connected  fila- 
ments) gelatinous,  definitely  formed  or  shapeless  fronds 
or  masses.  Filaments  jointed,  bearing  bristlelike  pro- 
cesses. Fructification,  zoospores  from  cell-contents  of  fila- 
ments, resting  spores  from  particular  cells  after  impregna- 
tion by  ciliated  spermatozoids  produced  in  antheridial  cells. 

1.  Draparnaldia. — Filaments  free,  primary  nearly  color- 
less, with  tufts  of  colored  ramuli  at  the  joints ;  zoospores 
formed  singly  in  the  joints  of  the  ramuli. 

2.  Ch&tophora. — Filaments     dichotomously     branched, 
aggregated  into  shapeless,  incrusted  or  branched,  gelati- 
nous   fronds,   the    joints   bearing    bristlelike    branches. 
Zoospores  (four  cilia)  solitary  in  the  articulations,  mem- 
branes of  filaments  very  fugacious.     (Little  green  protu- 
berances on  sticks,  etc.,  in  fresh  water.) 

C.  endivicefolia.  C.  tuberculosa.  C.  elegans.  C.  pisiformis. 
C.  dilatata.  C.  longceva. 

3.  Coleoch(Ete. — Frond    disk-shaped  or    irregularly  ex- 


APPENDIX.  383 

panded,  adherent  to  leaves,  etc.,  of  aquatic  plants,  formed 
of  jointed  dichotornous  filaments  radiating  from  a  centre, 
more  or  less  conjointed  laterally,  joints  producing  from 
the  back  a  slender  truncate  open  tube  from  which  a  long 
bristle  is  exserted.  Spores  and  zoospores  formed  in  the 
joints. 

4.  Ocklochcete. — Frond  discoid,  appressed,  filaments  cyl- 
indric,  radiating,  irregularly  branched,  of  a  single  series 
of  cells,  each  of  which  is  prolonged  above  into  an  inar- 
ticulate bristle.  0.  hystrix. 

4.  CONFERVACE^E. — In  sea  or  fresh  water,  filamentous, 
jointed,  without  evident  gelatin.  Filaments  variable,  sim- 
ple or  branched,  cells  more  or  less  filled  with  green,  or 
rarely  brown  or  purple,  granular  matter,  sometimes  ar- 
ranged in  peculiar  patterns  on  the  walls,  and  convertible 
into  spores  or  zoospores.  Not  conjugating. 

1.  Cladophora. — Filaments  tufted,  much  branched.   Sea 
and  fresh  water.     Zoospores  minute,  many  in  a  cell. 

C.  cepagropila. — Dense  balls  in  lakes,  etc. 
C.  crispata. — Yellowish  or  dull-green  strata. 

2.  Rhizoclonium. — Filaments    decumbent,    with    small 
rootlike  branches.      Zoospores  minute,  numerous.      Sea, 
brackish,  and  fresh  water. 

R.  rivulare. — Filaments  simple.     Bright-green  bundles, 
two  to  three  feet  long,  in  streams. 
JR.  tortuosum. — In  salt-water  pools. 
jR.  arenosum. — Dirty-green  strata,  on  sandy  seashores. 
R.  obtusangulum. — Sandy,  seashores. 
R.  riparium. 

R.  implexum. — On  mountain  rocks. 
jR.  arenicolum  (ditto). 

3.  Conferva. — Filaments  unbranched.  Zoospores  minute, 
numerous  in  the  cells.     Sea,  brackish,  and  fresh  water. 

C.  bombycina. — Yellow-green  cloudy  stratum  in  stagnant 
water. 


384  THE    MICROSCOPIST. 

C.floccosa. — More  robust,  articulations  once  or  twice 
longer  than  broad. 

C.  cerea. — Yellow-green  tufted  filaments,  thick  as  hog's 
bristles. 

C.  melagonium. — Erect  tufted  filaments. 

C.  linum. — Long,  tangled  filaments. 

4.  Ulothrix  (?). — Filaments   simple,   often  fasciculated, 
joints  short.     Zoospores  four  ciliated  ;  two,  four,  or  more 
in  a  cell.     Fresh  water. 

5.  Stigeodonium  (?). — Filaments  branched,  ramules  run- 
ning out  into  slender  points,  cell-walls  often  dissolving  to 
emit  zoospores.     Zoospores  four  ciliated,  one  in  a  cell. 

5.  ZYGNEMACE.E. — Fresh-water  filaments,  no  evident 
gelatin,  of  a  series  of  cylindric  cells,  straight  or  curved. 
Cell-contents  often  arranged  in  elegant  patterns  on  the 
walls.  Reproduction  from  conjugation  followed  by  a  true 
spore,  in  some  genera  dividing  into  four  sporules. 

1.  Zygnema. — Filaments    simple,    green    contents    ar- 
ranged in  two  globular  or  stellate  masses  in  each  cell. 
Conjugate  by  transverse  processes.     Spores  in  a  parent 
cell  on  cross  branch. 

*  Spores  in  one  of  parent  cells. 
Z.  cruciata. — Spores  globose. 

Z.  stagnalis. 
Z.  insignis. 
Z.  bicornis. 

*  *  Spores  in  cross  branches. 
Z.  immersa. 

Z.  conspicaa. 
Z.  decussata. 
Z.  RalfsiL 
Z.  pectinata. 

2.  Spirogyra. — Filaments  simple,  green  contents  in  one 
or  more  spiral  bands  on  cell-wall.     Conjugate  by  trans- 


APPENDIX.  385 

verse  processes.     Spores  in  one  of  parent- cells  (or  occa- 
sionally in  both). 

*  Spiral  band  single. 

8.  tenuissima.  S.  longata.  8.  inflata.  S.  communis.  8. 
quinina. 

*  *  Spirals  two. 

S.  decemina.     8.  elowgata. 

*  *  *  Spirals  numerous. 

S.  nitida.  8.  maxima.  8.  bellis.  8.  pellucida.  8.  rivu- 
laris.  8.  curvaia. 

3.  Zygogonium. — Filaments  simple  or  slightly  branched ; 
contents  diffused  or  in  two  transverse  bands.     Conjugate 
by  transverse  processes.    Spores  globose,  in  cross  branches, 
or    in   blind    lateral  pouches   without    conjugation.     Z. 
ericetorum. 

4.  Mesocarpus. — Filaments   simple,  with   contents   dif- 
fused.  Conjugate  by  transverse  processes,  from  which  the 
filaments  become  recurved.     Spores  in  cross  branches. 

M.  scalaris.     M.  depressus. 

5.  Staurocarpus. — Filaments   simple,  contents   diffused 
(rarely  in  moniliforrn  lines).   Conjugate  by  transverse  pro- 
cesses, from  which  the  filaments  become  recurved.    Spores 
(or  sporanges)  square  or  cruciate  in  dilated  cross  branches. 

8.  glutinosus.  8.  ccerulescens.  8.  quadratus.  S.  virescens. 
8.  gracillimus.  8.  gradlis. 

6.  Mougeotia. — Filaments  simple,  soon  bent  at  intervals  ; 
contents  mostly  diffused,  sometimes  in  several  serpentine 
lines.     Conjugate  by  the  inosculation  of  filaments  at  the 
convexity  of  the  angles.    Spores  not  known.    M.  genuflexa. 

6.  (EDOGONIACE^E. — Simple  or  branched,  fresh-water 
filamentous  plants,  attached,  without  gelatin.  Cell-con- 
tents uniform,  dense.  Cell-division  accompanied  by  cir- 
cumcissile  dehiscence  of  parent-cell,  producing  rings  on 
the  filaments.  Reproduction  by  zoospores  from  contents 
of  a  cell,  with  a  crown  of  cilia ;  resting  spores  in  sporan- 

25 


386  THE    MICROSCOPIST. 

gial    cells    after  fecundation   by  ciliated   spermatozoids 
formed  in  antberidial  cells. 

1.  (Edogonium. — Filaments  unbranched. 

*  Spores  globular. 

f  Sporanges  with  valvular  lid. 
(E.  rostellatum. — Monoecious, 
f  f  Sporanges  witb  lateral  orifice. 
£  Monoecious. 

(E.  curvun.     (E.  tumidulum. 
$  %  Gynandrosporous. 

(E.  Rothii.  (E.  depressum.  (E.  Braunii.  (E.  eckino- 
spermum,. 

*  *  Spores  oval. 

f  Sporanges  witb  valvular  lid. 

^  Gynandrosporous. 

(E.  dliatum. 

f  f  Sporanges  witb  lateral  orifice. 

^  Gynandrosporous. 

(E.  apophysatum. 

$  :f  Dioecious. 

(E.  gemelliparum. 

2.  Bulbochceta. — Filaments  brancbed  and  bearing  bristle- 
cells  witb  a  bulbous  base. 

7.  SIPHONACE.E.— Sea,  fresb  water,  or  on  damp  ground. 
Membranous  or  borny  hyaline  substance,  filled  with  green 
(in  Saprolegniese  colorless)  granular  matter.  Fronds  con- 
tinuous tubular  filaments,  free,  or  in  spongy  masses  of 
various  shapes,  crustaceous,  globular,  cylindric,  or  flat. 
Zoospores  single  or  numerous.  Resting  spores  in  spor- 
angial  cells  after  impregnation  by  contents  of  antheridial 
cells  of  different  form. 

1.  Codium. — Filaments  green,  branched,  interwoven  into 
spongiform  frond,  producing  biciliated  zoospores  in  spor- 
angial  cells  borne  on  the  sides  of  the  erect  clavate  branches. 
Marine. 


APPENDIX.  387 

2.  B'yopsis. — Filamentsgreen,  free,primately  branched ; 
two  or  four  ciliated  zoospores  in  extremities  of  branches. 
Marine.     1$.  plumosa.     B.  hypnoides. 

3.  Vaucheria. — Filaments  green,  more  or  less  branched, 
continuous,  producing  in  apices  large  solitary  zoospores 
covered  with  cilia,  also  bearing  lateral,  globose,  sporangial 
cells  and  hooklike  antheridial  cells  ("  horns  ").     Marine 
or  aquatic  or  on  damp  ground. 

4.  Botrydium. — Frond  a   spherical   green  vesicle  on  a 
ramified  filamentous  base,  the  cavity  of  the  whole  con- 
tinuous, the  ramified  base  producing  new  vesicles  (spor- 
anges)  by  stoloniferous  growth.     Multiplied  by  granular 
contents  of  vesicle  discharged  by  rupture  at  the  summit. 
Damp  grounds. 

5.  Hydrodictyon. — Frond    a    green   baglike  net,   with 
usually  pentagonal  open  meshes,  formed  of  cylindric  cells 
connected  by  their  ends.     Ciliated  zoospores  formed  in 
the  "  link  "-cells,  uniting  and  forming  a  miniature  net  be- 
fore escaping  from  parent-cell. 

6.  Achyla. — Filaments  colorless  or  light  brownish  (like 
mycelia  of   fungi) ;    free,  slightly   branched.     Numerous 
zoospores   in  apices  of  filaments,  and  spores  in  globose 
lateral  sporangial  cells.   On  dead  flies,  fishes,  or  sometimes 
on  decaying  vegetable  matter  in  water.     A.  prolifera. 

8.  OSCILLATORIACE.E. — Sea,  fresh  water,  or  damp  ground. 
Gelatinous  and  filamentous.  Filaments  slender,  tubular, 
continuous,  filled  with  colored,  granular,  transversely 
striate  substance,  seldom  branched,  though  often  coher- 
ing so  as  to  appear  branched  ;  usually  massed  in  broad 
floating  or  sessile  strata ;  very  gelatinous  ;  occasionally 
erect  and  tufted.  More  rarely  in  radiating  series  bound 
by  firm  gelatin,  and  then  forming  globose,  lobed,  or  flat 
crustaceous  fronds.  Contents  separate  into  roundish  or 
lenticular  gonidia. 

*  In  fresh  water  or  damp  earth. 


388  THE    MICROSCOPIST. 

a.  Stratum  ceruginous  or  blue-green. 

0.  limosa.  0.  tenius.  0.  muscorum.  0.  turfosa.  0. 
decor  ticans. 

b.  Stratum   dull  green  inclining  to  purple,  black,  or 
brown. 

0.  nigra.     0.  autumnalis.     0.  cortexta.     0.  ochracea. 
*  *  Marine  or  in  brackish  water. 

0.  littoralis. 

The  above  are  species  of  Oscillatoria. 

A.  OSCILLATORIE^E. — Filaments  transversely  striate  or 
moniliform,  sometimes  spirally  curled,  sheathed,  or  in  the 
minute  forms  without  evident  sheaths.  Spontaneous 
oscillating,  creeping,  or  serpentine  motion.  Increase  by 
transverse  division. 

1.  Bacterium. — Filaments  colorless,  very  small,  short, 
wand-shaped,   or   longish-oval,  with   two   to   four   cross 
striae,  exhibiting  vibratory  motion. 

2.  Vibrio. — Filaments  colorless,   very    slender,    monili- 
form.    Active  serpentine  motion. 

3.  Spirulina. — Filaments  green,  very  slender,  continu- 
ous or  moniliform,  curled  into  a  long  helical  or  screw 
form  ;  oscillating. 

4.  Didymohdix. — Filaments  brown,  very  slender,  con- 
tinuous, curled  spirally  and  twisted  in  pairs. 

5.  Oscillatoria. — Filaments   colored,  continuous,   trans- 
versely  striated,  readily  breaking  across  ;  a  proper  cellu- 
lar sheath  ;  oscillating  ;  in  strata  imbedded  in  gelatin. 

6.  Microcoleus. — Filaments  as  in  5,  but  in  bundles  in  a 
common  gelatinous  sheath,   tubular  and   dichotomously 
branched.     Filaments  oscillating. 

7.  Cwnocoleus. — Filaments    branched,   contained   in    a 
tough,  more  or  less  permanent  sheath,  which  bursts  ir- 
regularly.    Filaments  annulated. 

8.  Symploca. — Filaments  as  in  5,  but  erect  and  tufted, 
coherent  at  base,  bristling  above. 


APPENDIX.  389 

B.  LYNGBYE.E. — Filaments  motionless  (?),  oscillarioid, 
inclosed  in  distinct  sheath,  tufted  or  forming  strata,  with 
or  without  enveloping  jelly. 

9.  Dasygloea. — Filaments    unbranched.      Older  sheaths 
broad,  coalescent  outside  in  amorphous  gelatinous  stratum. 

10.  Lyngbya. — Filaments    elongated,    articulated,    un- 
branched ;  distinct  convoluted  cellulose  tube  ;  no  gelatin- 
ous matrix ;  articulations  close. 

11.  Leibleinia. — Filaments    short,    erect,    tufted,    un- 
branched  ;  distinct  cellulose  coat ;  free  ;  no  jelly. 

C.  SCYTONEME^;. — Filaments     articulated,    simple,    or 
branched,  motionless  ;  distinct  articulations  and  large  in- 
terstitial (propagative?)  cells;  sheaths  soften  and  swell, 
but  no  gelatinous  matrix. 

12.  Scytonema. — Filaments  ceespitose,  or,  more  rarely, 
fasciculate;  a  double  (lamellar)  gelatinous  sheath,  mostly 
closed  at  apex ;  branches  continuous  by  lateral  growing 
out  of  primary  filaments,  with  kneelike  base. 

13.  Desmonema. — Filaments  branched,  more  or  less  co- 
herent ;  primary  branches  with  connecting  cell  at  base ; 
secondary  branches  without  cell,  annulated. 

14.  Arthronema. — Filaments  articulated,  simple, in  short 
lengths,  overlapping  at  their  ends  in  gelatinous  sheath. 

15.  Petalonema. — Filaments  branched;  outer  sheaths  of 
joints  expanded  upwards  and  outwards  into  funnel-shaped 
bodies,  each  partly  overlapping  its  successor,  forming  a 
common   obliquely   lamellated   and    transversely   barred 
gelatinous  cylinder. 

16.  Calothrix. — Filaments    closely    articulated,  tufted, 
with  branches  in  apposition  for  some  distance,  here  and 
there  cohering  laterally;  sheaths  firm,  often  dark-colored. 

17.  Tolypothrix. — Filaments  free,  radiantly   or  fastigi- 
ately  branched,  distinctly  articulated  at  bases  of  branches, 
which  are  continuous  by  ex-current,  not  in  apposition  ; 
sheaths  thin,  hyaline. 


390  THE    MICROSCOPIST. 

18.  Sirosiphon. — Filaments  single,  double,  or  triple,  in 
distinct  common  sheath,  articulated,  branched  by  lateral 
budding ;  branches  divergent. 

19.  Sehizothrix. — Filaments     branched     by     division ; 
sheaths  lamellated,  thick,  rigid,  curled,  thickened  below, 
finally  longitudinally  divided. 

20.  Sympkyosipkon. — Filaments  erect  or  ascending,  in- 
closed in  lamellated  hard  sheaths,  concreted  laterally  at 
their  bases,  involved  in  jelly. 

21.  Rhizonema. — Sheath   cellular,  with   branched   and 
anastomosing    rootlets   (?) ;    filaments    annulated,   inter- 
rupted here  and  there  by  a  connecting  cell ;  branches  in 
pairs  from  protrusion  of  filament. 

D.  RIVULARIE^E. — Filaments  articulated ;  enlarged  basal 
cell,  attenuated  above,  connected  into  definite  or  indefinite 
fronds ;  motionless. 

22.  Schizosiphon. — Basal  cells  globose;  filaments  simple, 
sheathed;   sheaths  in  groups,  dark-colored,  hard,  open, 
and  expanded  above,  and  overlapping  so  as  to  form  a 
succession  of  ochrese,  which  have  the  free  borders  slit  up 
into  filaments  or  fringes;  also  displaying  a  spiral  struc- 
ture in  dissolution. 

23 .  Physactis. — Filaments  whip-shaped,  torulose  at  base ; 
sheaths  simple,  gelatinous,  in  a  globose  and  solid,  or  sub- 
sequently a  bullose,  vesicular  frond  ;   in  globose  fronds 
filaments  radiate  from  centre,  in  vesicular  from  internal 
(lower)  surface  of  gelatinous  matrix. 

24.  Ainactis. — Filaments    branched,    articulate ;     thin 
sheaths  in  solid  pulvinate  frond,  which  is  concentrically 
zoned  by  the  dichotomous  branching  of  filaments  ;  sheaths 
more  or  less  solidified  by  carbonate  of  lime  ;  sometimes  a 
spiral  structure  in  dissolution. 

25.  Rivularia. — Filaments  with  an  oval  basal  cell,  suc- 
ceeded by  a  cylindric  manubrium,  the  remainder  short, 
attenuated   upwards  (whip-shaped) ;   sheaths   sometimes 


APPENDIX.  391 

saccate  below,  open  (not  fringed)  above,  forming  a  slippery 
gelatinous  frond. 

26.  Euactis. — Filaments    whip-shaped,  with    repeated 
ochreate  sheaths,  forming  fronds  in  which  they  radiate, 
and  by  superposition  of  successive  generations  form  con- 
centric layers  ;   the  ochreate  sheaths  are  cartilaginous, 
lamellated,  united  laterally,  funnel-shaped,  fringed  at  open 
edge. 

27.  Inomeria. — Filaments  whip-shaped,  vertical,  paral- 
lel ;  obscure  sheaths  decomposed  into  slender  filaments, 
forming  crustaceous  fronds,  becoming  stony. 

28.  Petronema. — Densely    csespitose,    erect,    somewhat 
regularly  branched  ;  branches  free,  with  obtuse  rounded 
apices,  and  each  with  connecting  cell  at  base  ;  filaments 
annulated  and  growing  thicker  upwards. 

E.  LEPTOTHRICE.E. — Doubtful  Oscillatoriacese. 

29.  Leptothrix. — Filaments  very  slender,  neither  articu- 
lated, branched,  concreted,  nor  sheathed. 

30.  Hypheothrix. — Filaments  unbranched,  inarticulate, 
sheathed,  interwoven  in  more  or  less  compact  stratum. 

31.  Symploca. — Filaments  unbranched,  sheathed,  inar- 
ticulate, concreted  into  branches,  conjoined  at  their  bases; 
sheath  a  simple  hyaline  membrane. 

9.  NOSTOCHACE,B. — Gelatinous  Fresh  water,  or  in  damp 
mosses,  etc. ;  soft,  or  almost  leathery,  of  variously  curled 
or  twisted  necklace-shaped  filaments,  colorless  or  green, 
composed  of  simple  (or  double)  rows  of  cells,  contained  in 
a  gelatinous  matrix  of  definite  form,  or  heaped  without 
order  in  a  gelatinous  mass.  Some  cells  enlarge  and  form 
vesicular  empty  cells  or  sporangial  cells ;  reproduce  by 
breaking  up  the  filaments,  and,  by  resting  spores  formed 
singly  in  the  sporanges. 

1.  Nostoc. — Phycoma,  or  general  mass  of  plant  in  a  film 
formed  by  condensation  of  the  surface ;  globose,  or  spread 


392  THE    MICROSCOPIST. 

out ;  form  variable,  gelatinous  or  mucous,  coriaceous,  soft 
or  hard,  elastic,  slimy,  containing  simple,  curved,  and  en- 
tangled moniliform  colorless  or  greenish  filaments,  com- 
posed of  cells,  which  seem  solid,  imbedded  in  amorphous 
gelatinous  matrix ;  heterocysts  globose,  interstitial,  larger 
than  ordinary  joints  of  filaments. 

N.  commune.  N.  cceruleum.  N.  verruconum.  N.  minat- 
issimum.  N.  lichenoides.  N.  vesicarium.  N.  sphcericum. 
N.  pruniforme.  N.foliacum. 

2.  Monormia. — Frond  or  phycoma   definite,  gelatinous, 
elongated,  linear;  spirally  curled  and  convoluted  sheath, 
inclosing  a  single  moniliform  filament  ;  heterocysts  inter- 
stitial;  sporanges  from  joints  most  distant  from  vesicular 
cells.     M.  intricata. 

3.  Anabaina. — Filaments  moniliform  or  cylindric,  often 
curled,  in  formless  mucous  matrix,  often  forming  a  float- 
ing film,  with  vesicular  cells  (heterocysts)  and  sporangial 
cells. 

*  Without  a  membranous  sheath. 

a.  Trichormus. — Heterocysts  interstitial  and  terminal ; 
sporanges  first  from  cells  most  distant  from  heterocysts. 

b.  Sphazrozyga.  —  Heterocysts    interstitial ;    sporanges 
from  nearest  cells. 

c.  Cylindrospermum. — Heterocysts  terminal ;  sporanges 
as  last. 

d.  Dolichospermum. — Heterocysts  interstitial ;  sporanges 
indefinite  and  unequal. 

*  *  Filaments  not  included  in  membranous  sheath. 

e.  Aphanizomenon. — Heterocysts    none   (?) ;    sporanges 
usually  simple  and  unequal. 

f.  Sperm.osira. — Heterocysts    interstitial,   single   or   in 
pairs  ;  sporanges  as  in  Trichormus. 

10.  ULVACE^E. — Marine  or  fresh-water  Algse,  membra- 
nous, flat,  and  expanded  ;  tubular  or  saccate  fronds,  com- 
posed of  polygonal  cells  firmly  conjoined  by  their  sides  ; 


APPENDIX.  393 

zoospores  formed  from  cell-contents  and  breaking  out  from 
the  surface,  or  motionless  spores  from  the  whole  contents 
of  a  cell. 

1.  Ulva. — Frond  plane,  simple,  or  lobed,  of  double  layer 
of  cells,  closely  packed,  producing  zoospores.     U.  lactuca. 
(latissima)  U.  Linza. 

2.  Enter omorpha. — Frond  hollow,  simple,  or  branched, 
of  a  single  layer  of  cells,  closely  packed,  forming  a  sac  or 
tube,  with  zoospores.     E.  intestinalis. 

3.  Monostroma. — Frond  flat  or  saccate,  simple  or  lacer- 
ate-lobed,  forming  a  single  layer  of  cells,  which  are  scat- 
tered in  a  homogeneous  membrane,  with  zoospores.     M. 
buUosum. 

4.  Prasiola. — Frond  membranous,  lacerate-lobed,  of  sin- 
gle layer  of  cells  in  simple  or  compound  lines,  or  groups 
multiple  of  four ;  spores  from  whole  contents  of  cells,  mo- 
tionless.    P.  callophylla,  crispa,  furfur  acea,  and  stipitata. 

5.  Schizogonium. — Frond  filiform,  dilated  here  and  there 
into  flat  ribands,  with  two  or  four  rows  of  cells ;  spores 
from  whole  contents,  motionless.     8.  percursum.     S.  Icete- 
vireus.     S.  murale. 

11.  PALMELLACE^E. — Plants  forming  gelatinous  or  pul- 
verulent crusts  on  damp  surfaces  of  stone,  wood,  etc. 
Masses  of  gelatinous  substance,  or  pseudo-membranous 
expansions  or  fronds,  of  flat,  globular,  or  tubular  form,  of 
one  or  numerous  cells,  with  green,  red,  or  yellowish  con- 
tents ;  spherical  or  elliptical  form,  the  simplest  being  iso- 
lated cells  (in  groups  of  two,  four,  eight,  etc.) ;  others 
formed  of  some  multiple  of  four,  the  highest  of  compact, 
numerous,  more  or  less  closely  conjoined  cells.  Reproduce 
by  cell-division,  by  conversion  of  cell-contents  into  zoo- 
spores,  and,  by  resting  spores  formed  sometimes  after 
conjugation,  in  other  cases  probably  after  fecundation  by 
spermatozoids. 


394  THE    MICROSCOPIST. 

*  Plants  with  a  frond  of  colorless  gelatinous  substance. 
f  Frond  amorphous. 

1.  Palmella. — Frond   a   slimy  stratum,  crowded  with 
large  globular  cells,  multiplying  by  division ;  green  and 
red.     P.  cruenta. 

2.  Microhaloa.  —  Frond    mucoid,   floating    in    water, 
crowded   with    minute   cells,  multiplying    by   division ; 
green  and  red. 

f  f  Frond  definite. 

3.  Glceocarpus. — Frond  of  cells  in  wide  gelatinous  coats, 
inclosed  in  similar  coats  of  parent-cells  for  several  genera- 
tions. 

4.  Botrydina. — Frond  globose,  the  periphery  of  cells  co- 
hering into  a  sort  of  cellular  epiderm,  the  inner  cells  free. 

5.  Clathrocystis. — Frond  gelatinous,  first  globose,  then 
hollow,  then  broken  by  irregular  expansion  into  a  coarse 
net, finally  breaking  up;  frond  crowded  with  minute  cells, 
multiplied  by  division. 

6.  Coccochloris. — Frond  globose,  gelatinous,  containing 
numerous  distinct  cells,  all  free. 

7.  Merismopoedia. — Frond  very  minute,  flat,  square,  ge- 
latinous ;  cells  in  families  of  four,  sixteen,  and  sixty-four. 

8.  Urococcas.  —  Frond   of    streaked   gelatinous    tubes, 
formed  of  ensheathing  parent-cell  membrane  in  a  single 
row,  with  cells  solitary  or  byinary  (from  division)  in  ends 
of  the  tubes. 

9.  Hormospora. — Frond  a  wide,  gelatinous,  simple,  or 
branched  sheath,  with*  single  row  of  cells  in  twos  or  fours. 

10.  Tetraspora. — Frond  gelatinous,  more  or  less  foliace- 
ous  ;  cells  in  fours,  ultimately  becoming  free  as  zoospores. 

11.  Hydrurus. — Frond  toughly  gelatinous, filiform,  with 
imbedded  longitudinal  rows  of  cells. 

12.  Palmodictyon. — Frond  gelatinous,  filiform, branched ; 
branches  dividing  and  anastomosing  into  a  net,  consisting 
of  large  vesicular  cells  with  colored  contents,  which  escape 
as  zoospores. 


APPENDIX.  395 

*  *  Plants  of  single  cells,  solitary,  or  united  in  small 
numbers  into  families.     (Unicellular  Algse.) 
f  Solitary  cells. 

13.  Schizochlamys. — Cells  free,  globular,  aggregated  in 
jelly,  each  dividing  into  two  or  four,  set  free  by  parent- 
cell  breaking  into  two  or  four  segments ;  green. 

14.  Chlorospkcera. — Unicellular,  free;    a  large  globose 
cell  with  green  contents,  dividing  into  two,  in  each  of 
which  is  formed  a  new  cell  like  the  parent,  set  free  by 
lateral  rupture  of  parent-cell  membranes. 

15.  Charadum. — Unicellular  ;  a  minute,  attached,  pyri- 
form,  fusiform,  or  subglobose  sac,  shortly  stipitate,  con- 
taining green  protoplasm,  which  by  oft-repeated  binary 
division  forms  a  swarm  of  active  two-ciliated  zoospores, 
escaping  by  a  lateral  or  terminal  slit. 

16.  Apiocystis. — Simple  attached  sac  with  stout  mem- 
brane ;  green  contents  ;  at  first  groups  of  four  still  go- 
nidia, which  subdivide  repeatedly,  and  as  the  parent-sac 
grows  become  active  zoospores,  which  move  in  parent-sac, 
and  then  break  out  in  a  swarm. 

17.  Codiolum. — Attached,  small,  long,  clavate  sac,  at- 
tenuated below  into  a  solid  stipe,  tilled  with  granular 
green  contents  and  starch  granules,  ultimately  converted 
at  once  into  many  gonidia,  escaping  by  rupture  of  apex ; 
gonidia  globose. 

18.  Jrlydrocytium. — Attached  minute  oblong  sac  ;  short 
hyaline  stalk  ;  green  contents  ;  parietal  starch-corpuscle  ; 
contents  divided  at  once  into  many  two-ciliated  zoospores, 
lying  on  the  wall,  then  moving  actively  and  breaking  out 
into  a  swarm. 

19.  Ophiocytium. — Minute,  elongated,  cylindric,  curved 
sac ;  short  stipe ;  free  or  attached ;  green  contents  scat- 
tered ;  finally  eight  gonidia  in  a  single  row,  set  free  by 
circumcissile  rupture  of  end  of  sac. 

20.  Sciadium. — First  a  minute,  solitary,  attached,  elon- 
gate, tubular,  stipitate  sac,  with  eight  gonidia  in  single 


396  THE    MICROSCOPIST. 

row  ;  apex  of  sac  opens  by  circumcision,  and  the  gonidia 
grow  out  into  tubes  like  the  parent  in  an  umbel,  their 
stipes  remaining  inserted  ;  each  new  tube  repeats  this  to 
fourth  or  more  generation,  the  last  generation  from  the 
compound  umbel  emitting  its  gonidia  as  two-ciliated  zoo- 
spores. 

21.  Chytridium. — Parasitic ;  minute  globular  pyriform 
or  urceolate  sac,  attached  by  a  foot  which  penetrates  into 
the  supporting  body  (mostly  a  Confervoid) ;  cell-contents 
colorless,  becoming   two-ciliated    zoospores,  escaping   by 
dehiscence  of  a  valvelike  lid,  or  by  simple  rupture  of  sac. 

22.  Pythium. — Parasitic  ;  a  globular  sac  in  the  interior 
of  cell  of  diseased  Confervoids,  often  in  groups ;  contents 
colorless ;  sac  grows  to  flasklike  form,  the  neck  perforat- 
ing the  wall  of  the  nurse-plant  and  bursting  to  emit  ac- 
tive gonidia  (?). 

12.  VOLVOCINE^E. —  Microscopic,  cellular;  fresh-water 
groups  of  bodies,  like  zoospores,  connected  into  four  by 
enveloping  membranes ;  either  assemblages  of  coated  zoo- 
spores  by  cohering  membranes,  or  of  naked  zoospores  in 
a  common  membrane;  the  zoospore-like  two-ciliated  bodies 
perforate  the  coat,  and  by  conjoined  action  move  the  entire 
group;  reproduce  by  division  (Gonium)^  or  by  single  cells 
becoming  families  (Pandorina,  Volvoz),  and,  by  resting 
spores,  formed  after  impregnation  of  some  cells  by  sperma- 
tozoids  formed  from  contents  of  other  cells. 

Solitary : 

No  cilia,  Gyges. 

A  pair  of  cilia,  PROTOCOCCUS. 

Grouped : 

Square  layer,  gonidia  of  2  cilia,  GONIUM. 


APPENDIX.  397 

Forming  a  spherical  body : 
Cilium  solitary. 
With  a  tail,  Uroglena. 
Without  a  tail. 
Without  eye-spot. 
With  special  coats,  Syncrypta. 
With  eye-spot. 

Gonidia  dividing  into  clusters,  Spharosira. 
Cilia  2. 

No  eye-spot,  Synura. 
With  eye-spot. 
Common  envelope  spherical. 
Gonidia  numerous,  all  over  periphery,  VOL  vox. 
Gonidia  8,  in  a  circle  at  the  equator,  STEPHANOSPH^RA. 
Envelope  ellipsoidal,  gonidia  16  or  32,  perhaps  stages 
of  Volvox  or  Pandorina. 

13.  DESMIDIACE^;. — Microscopic, gelatinous, green;  cells 
without  siliceous  coat;  forms  varied,  as  oval,  crescentic, 
cylindric,  etc.,  with  a  more  or  less  stellate  appearance, 
having  a  bilateral  symmetry,  the  junction  being  marked 
by  a  division  of  the  green  contents ;  individual  cells  free 
or  grouped.  Reproduction  by  division  and  by  resting 
spores  produced  in  sporangia  formed  after  conjugation  of 
two  cells  and  union  of  their  contents,  and  by  zoospores 
formed  in  the  vegetative  cells  or  in  the  germinating  rest- 
ing spores. 

I.  CLOSTERIEJE. — Cells  single,  elongated,  never  spinous, 
often  not  constricted  in  the  middle ;  sporangia  smooth. 

1.  Closterium. — Cell  crescent-shaped,  or  much  attenu- 
ated at  the  ends,  not  constricted  in  the  middle. 

2.  Penium. — Cell  straight,  not,  or  very  little  constricted 
in  the  middle,  rounded  at  both  ends. 

3.  Tetmemorus. — Cell  straight,  constricted,  notched  at 
ends. 


398  THE    MICROSCOPIST. 

4.  Doddium. — Cell   straight,   constricted,   truncate   at 
ends. 

5.  Spirotcenia. — Cell   straight,   not   constricted  ;    endo- 
chrome  spiral. 

IT.  COSMARIEJE. — Cells  single,  distinctly  constricted  in 

O        '  »/ 

the  middle  ;  segments  seldom  longer  than  broad ;  sporan- 
gia spinous  or  tuberculated. 

6.  Micrasterias. — Lobes  of  the  segments  incised  or  bi- 
dentate. 

7.  Euastrum. — Segments  sinuated,  generally  notched  at 
ends,  and  with  inflated  protuberances. 

8.  Cosmarium. — Segments  neither  notched  nor  sinuated, 
end  view  elliptic,  circular,  or  cruciform. 

9.  Xanthulium. — Segments  compressed,  entire,  spinous. 

10.  Arthrodesmus.  —  Segments   compressed,  each   with 
only  two  spines. 

11.  Stturastrum. — End  view  angular,  radiate,  or  with 
elongated  processes  which  are  never  in  pairs. 

12.  Didymocladon. — End  view  angular,  each  angle  with 
two  processes,  one  inferior  and  parallel  with  that  of  other 
segment,  the  other  superior  and  divergent. 

III.  DESMIDIE.E. — Cells  united  into  an  elongated  jointed 
filament ;  sporangia  spherical,  smooth. 

13.  Hyalotheca. — Filament  cylindric. 

14.  Didymoprium. — Filament  cylindric  or  subcylindric  ; 
cells  with  two  opposite  bidentate  projections. 

15.  Desmidium. — Filament  triangular  or  quadrangular ; 
cells  with  two  opposite  bidentate  projections. 

16.  Aptogonum. — Filament   triangular   or   plane,  with 
foramina  between  the  joints. 

17.  Sphcerozosma. — Filament  plane  ;  margins  incised  or 
sinuate  ;  joints  with  junction  glands. 


APPENDIX.  399 

IY.  ANKISTRODESMI^E.  —  Cells   elongate,  entire,  small, 
grouped  in  fagot-like  bundles. 

18.  Ankistrodesmus. 

Y.  PEDIASTRE.E. — Cells  grouped  in  the  form  of  a  disk 
or  star,  or  placed  side  by  side  in  one  or  two  short  rows. 

19.  Pediastrum. — Cells  forming  a  disk  or  star,  marginal 
cells  bidentate. 

20.  Monactinus. — Cells  as  in  19,  but  marginal  cells  uni- 
dentate. 

21.  Scenedesmus. — Cells  placed  side  by  side  in  one  or 
two  rows. 

14.  DIATOMACEJE. — For  genera,  see  page  142. 


INDEX  AND   GLOSSAEY 

OF  TEEMS  USED  IN  THE  MICROSCOPIC  SCIENCES. 

The  figures  refer  to  the  page. 


Aberration,  22  (Lat.  ab,  from,  and  erro,  to  wander). — Errors 
resulting  from  imperfection  of  lenses. 

Aberrant. — Differing  from  customary  structure. 

Abnormal  (Lat.  ab,  and  norma,  a  rule). — Contrary  to  usual 
structure. 

Abiogenesis,  125  (Gr.  a,  privative  ;  bios,  life;  and  gennao,  to 
produce). — Spontaneous  generation,  or  production  without  pre- 
existing life. 

Absorption  Bands,  18,  45, 101. — Lines,  more  or  less  distinct, 
produced  in  the  spectrum  by  certain  transparent  substances. 

Abranchiate  (Gr.  a,  without ;  bragchia,  gills). 

Acalephs,  166  (Gr.  akalephe,  a  nettle). — Sea  nettles,  or  jelly- 
fish. Their  power  of  stinging  is  caused  by  microscopic  thread- 
cells  in  the  integument. 

Acanthocephali,  335  (Gr.  akantha,  a  spine,  and  Jcepliale,  a 
head). — An  order  of  parasitic  worms. 

Acanthacese. — A  natural  order  of  plants.  The  seeds  of  many 
genera  have  hygroscopic  hairs  with  spiral  fibres,  which  make 
them  interesting  microscopic  objects. 

Acarinae,  179,  338  (Gr.  akari,  a  mite). — An  order  of  the 
Arachnidae,  of  which  the  cheese-mite  is  the  type. 

Acephalocyst  (Gr.  a,  kephale,  kustis,  a  headless  bladder). — 
Simple  sacs  filled  with  transparent  liquid,  usually  known  as 
hydatids.  They  are  the  cysts  of  Echinococci,  in  which  the 
animals  have  disappeared  or  have  been  overlooked. 

26 


402  INDEX    AND    GLOSSARY. 

Acetic  acid,  67. 

Acetate  of  potass,  75. 

Achyla,  136. — -Microscopic  plants,  either  Algae  or  fungi, 
found  parasitically  on  the  bodies  of  dead  flies  in  water,  also 
on  fish,  etc. 

Achorion  Schcenleinii,  329. — A  microscopic  vegetation  oc- 
curring infavus  (a  skin  disease). 

Achromatic  (Gr.  a,  and  chroma,  color). — Without  chromatic 
aberration. 

Achromatic  object-glasses,  25. 
44  condenser,  33. 

Acinetse,  162  (Gr.  akinete,  fixed). — Infusorial  animals,  for- 
merly supposed  to  be  intermediate  stages  in  the  development 
of  Vorticellae. 

Accessories,  microscopic,  32. 

Actinia,  165  (Gr.  aktin,  a  sun  ray), — Sea  anemones,  or  Ac- 
tinoid  polyps.  Formerly  called  animal  flowers. 

Acids,  tests  for,  109. 

Adenoma,  272,  287  (Gr.  aden,  a  gland). — A  glandular  tu- 
mor. 

Adenoid  Tissue,  194. — Glandular  tissue. 

Adulteration  of  food,  323. 

Adjustment,  51. 

JEcidium,  363  (Gr.  wheel-like].  —  Minute  parasitic  fungi 
(Order,  Coniomycetes  or  Uredoideae),  like  little  cups  with  red- 
dish or  brownish  spores  when  mature.  Earlier  they  are  mi- 
nute spots  on  the  plants  they  infest.  Known  as  "  blight," 
44  brand,"  etc. 

^Etiology,  321  (Gr.  treatise  on  causes'). — The  doctrine  of 
the  causes  of  disease. 

JEroscope,  321. 

Agriculture,  microscope  in,  18. 

Air-pump,  79. 

Albuminous  infiltration,  244. 
44  compounds,  184. 

Albuminuria,  303. 

Alcohol,  68,  108,  252. 

44       and  acetic  acid,  68. 
44       and  soda,  68. 


INDEX    AND    GLOSSARY.  403 

Alkalies,  tests  for,  108. 

Alkaloids,  tests  for,  18,  111. 

Allantois,  204  (Gr.  sausage-like). — An  oblong  sac  developed 
in  the  embryonic  life  of  animals  near  the  end  of  the  intestine, 
and  serving  for  temporary  respiration. 

Alcyonium,  165. — A  genus  of  Coralline  polyps. 

Algae,  139  (Lat.  sea  weeds}. — The  great  variety  in  form  and 
organization  shown  by  this  class  of  plants  render  it  an  inter- 
esting field  of  microscopic  research.  The  families  of  Desmids 
and  Diatoms  have  been  particular  favorites. 

Alternation  of  Generations,  126. — This  term  denotes  a  form 
of  reproduction  in  which  the  }?oung  do  not  resemble  the  parent 
of  the  animal  but  the  grandparent. 

Alimentary  canal  in  insects,  177. 

Amides,  184. — A  term  used  in  chemistry  to  express  a  com- 
pound ammonia,  in  which  one,  two,  or  three  of  the  hydrogen 
atoms  are  replaced  by  an  acid  radical. 

Ammonia.  — Volatile  alkali.  Used  in  preparing  carmine 
fluids,  69,  72.  Test  for  ammonia,  107.  Used  as  a  test,  108, 
111,  112.  The  crystals  of  ammoniacal  salts  are  often  beautiful 
microscopic  objects.  The  hydrochlorate  forms  cubes,  octahe- 
dra,  and  trapezohedra,  but  if  crystallized  rapidly  makes  pecu- 
liar feathery  crystals.  It  does  not  polarize.  Crystals  of  oxa- 
late,  oxalurate,  and  purpurate  of  ammonia  are  beautiful  objects 
for  the  polariscope. 

Ambulacra  (Lat.  ambulacrum,  a  place  for  walking). — Holes 
or  avenues  in  the  shell  through  which  the  tube  feet  of  Echino- 
derms  are  protruded. 

Amnion,  204  (Gr.  amnos,  a  lamb). — One  of  the  fetal  mem- 
branes of  the  higher  vertebrates. 

Amoeba,  121  (Gr.  amoibos,  changing). — Animals  of  simplest 
form,  composed  of  a  glutinous  living  substance  or  bioplasm. 

Amoeboid  Cells,  121,  128. — Cells  with  movements  similar  to 
Amoeba  have  been  found  in  vegetables  as  well  as  animals.  See 
Bioplasm. 

Amplifier,  26,  346. 

Amphipleura  Pellucida,  56. — A  test  diatom  for  high  powers. 
The  valves  are  linear  lanceolate,  with  a  median  longitudinal 
line.  No  median  nodule.  The  striae  are  exceedingly  fine. 


404  INDEX    AND    GLOSSARY. 

Amylum,  132  (Gr.  amuloa,  starch). — Starch. 

Amyloid. — A  vegetable  substance  analogous  to  starch,  but 
turning  yellow  in  water  after  having  been  colored  blue  by 
iodine. 

Amyloid  Cell  and  Infiltration,  239. — A  waxy  or  lardaceous 
albuminate  infiltrated  among  the  tissues. 

Analogy. — Resemblance  in  form  but  not  in  function,  or  in 
function  but  not  in  form. 

Analysis  of  urine,  300. 

Analytic  Crystals,  90, 113. — Crystals  which  analyze  polarized 
light,  as  tourmaline,  nitrate  of  potass,  boracic  acid,  uric  acid, 
iododisulphate  of  quinia. 

Anatomy  of  insects,  17T. 

Angioma,  269  (Gr.  angion,  a  vessel). — Blood  tumor. 

Anguillula,  171  (Lat.  anguis,  a  snake). — A  genus  of  minute 
animals,  formerly  classed  among  Infusoria,  but  now  regarded 
as  nematoid  Eutozoa.  The  t;  eels  "  in  sour  paste  and  vinegar 
belong  here. 

Angular  Aperture,  25. — The  angle  measured  by  the  arc  of 
a  circle,  the  centre  of  which  is  formed  by  the  focal  point  of  the 
objective,  the  radii  being  formed  by  the  most  extreme  lateral 
rays  which  the  object-glass  admits. 

Anilin  Staining -fluids,  69.  Anilin  Carmine,  69. — Anilin 
colors  are  of  great  interest  in  chemistry  and  microscopy. 
Anilin  is  a  base,  forming  salts  with  various  acids,  as  hydro- 
chlorate,  nitrate,  and  oxalate  of  anilin.  The  substitution  deri- 
vatives of  anilin  are  very  complex  and  their  colors  various. 
Mauvine  forms  a  purple  solution  ;  rosanilin,  known  also  as 
fuchsin,  magenta,  etc.,  a  deep  red ;  Hoffman's  violet  a  rich 
violet;  anilin  blues  are  numerous.  There  are  also  several  ani- 
lin greens,  and  chrysanilin  dyes  a  golden  yellow. 

Animal  parasites,  330. 

Animalcule,  160. — (A  little  animal.)  Usually  applied  to  In- 
fusoria, Rotatoria,  etc.,  but  formerly  given  also  to  many  of  the 
lower  Algae. 

Animalcule  cage,  41. 

Animal  histology,  182. 

Annelidse,  337. — A  gallicized  form  of  Annulata. 

Annulata,  172. — Ringed  worms. 


INDEX    AND   GLOSSARY.  405 

Annual  Rings,  156. — Concentric  rings  seen  in  sections  of 
Dicotyledonous  stems.  They  probably  indicate  periods  of  foli- 
age, and  more  than  one  may  be  produced  in  a  year. 

Androspore,  152  (Gr.  a  male  seed). — A  peculiar  body  set 
free  from  a  germ-cell  during  the  development  of  (Edogonium, 
and  probably  some  other  Confervacese. 

Annulus  of  Ferns,  155. — The  ring  surrounding  the  capsule 
which  contains  the  spores. 

Anomalous. — Irregular,  contrary  to  rule. 

Antennae,  175  (Lat,  antenna,  a  yard-arm). — The  jointed  horns 
or  feelers  of  most  Articulata. 

Anther,  157  (Gr.  anthos,  a  flower). — The  case  which  contains 
the  pollen  of  a  plant. 

Antheridia,  154. — The  so-called  male  organs  of  urn  mosses 
and  similar  plants. 

Antherozoids,  152. — The  fertilizing  cells  of  some  of  the  Con- 
fervacese. Used  also  synonymously  with  Spermatozoids. 

Aphides,  126. — Plant  lice.  Order,  Hemiptera.  Their  pro- 
duction is  an  example  of  the  alternation  of  generation  as  well 
as  parthenogenesis, 

Aphtha,  329  (Gr.  to  fasten  upon). — Thrush,  or  muguet,  a 
disease  of  the  mouth,  etc.,  in  children,  or  in  adults  towards  the 
fatal  termination  of  chronic  disease.  Supposed  to  be  the  pro- 
duct of  Oidium  albicans,  or  thrush  fungus. 

Aplanatic,  26  (Gr.  without  deviation). — Refers  generally  to 
spherical  aberration  in  lenses. 

Apothecia,  154. — The  shields  of  Lichens ;  firm  horny  disks 
arising  from  the  thallus,  etc.,  containing  spores. 

Aqueous  humor,  220. 

Arachnida,  338  (Gr,  arachne,  the  spider). — The  class  of 
animals  containing  spiders,  scorpions,  mites,  etc. 

Arachnoid  Membrane,  225. — A  delicate  cobweb-like  mem- 
brane between  the  pia  mater  and  dura  mater  of  the  brain. 

Arachnoidiscus,  148. — A  beautiful  circular  Diatom.  The 
markings  vary.  A.  Ehrenbergii  is  common  on  the  Pacific 
coast. 

Arcella,  159  (Lat.  area,  a  chest). — A  genus  of  Rhizopods. 
The  test  of  the  common  species,  A.  vulgaris,  has  delicate 
markings  like  the  valves  of  Diatoms. 


406  INDEX    AND    GLOSSARY. 

Archeus,  116. — In  the  theory  of  Yan  Helmont,  the  specific 
agent  presiding  over  vital  functions. 

Archegonium,  155  (Gr.  arche,  beginning  ;  gone,  seed). — The 
early  condition  of  the  spore-case  in  mosses,  ferns,  etc.  Also 
called  Pistillidium. 

Arteries,  201. — Tubes  conveying  blood  from  the  heart  to  the 
capillaries.  They  have  three  coats,  an  outer,  middle,  and  in- 
ner coat.  The  inner  is  epithelial,  the  middle  of  unstriped 
muscle,  and  the  outer  of  fibrous  connective  tissue.  Thej^  are 
all  supplied  with  nutrient  bloodvessels,  the  vasa  vasorum,  and 
have  nerves  from  the  ganglionic  and  spinal  systems. 

Arsenic,  Tests  for,  110. — Arsenious  acid.  The  most  com- 
mon form  of  cr}Tstal  is  octohedral  or  tetrahedral,  but  a  right 
rhombic  form  may  be  obtained  by  sublimation.  Protoxide  of 
antimony  will  also  yield  by  sublimation  similar  crystals,  re- 
quiring discrimination  in  cases  of  poisoning. 

Arthritic  deposits,  241  (Gr.  arthron.  a  joint). 

Areolar  fibroma,  268. 

Ascaris,  336  (Gr.  askeris,  a  round  worm). 

Asci,  154  (Gr.  askos,  a  bottle). — A  long  or  roundish  spore- 
case  of  fungi,  containing  spores.  Called  also  thecse. 

Ascomycetes,  138. — An  order  of  fungi  characterized  by 
asci. 

Asellus,  172. — A.  vulgaris,  or  water  woodlouse,  an  Isopod 
crustacean,  is  interesting  to  the  microscopist  since  its  trans- 
parency permits  a  view  of  the  circulation. 

Aspergillus,  136,  325. — A  genus  of  Mucedines,  forming 
moulds,  as  the  blue  mould  on  cheese,  etc. 

Asterias,  168  (Gr.  aster,  a  star). — Star-fish. 

Atheroma,  234  (Gr.  porridge  of  meal). — A  disease  of  the  ar- 
teries characterized  by  a  pulpy  deposit. 

Atrophy  of  heart,  242  (Gr.  a  trophe,  not  nourishing). 

Avanturine. — A  mineral  sometimes  seen  in  cabinets  consist- 
ing of  silex  and  scales  of  mica.  Artificial  avanturine  is  of 
glass  with  crystals  of  metallic  copper  scattered  through  it. 

Amcularia,  169  (Lat.  avicula,  a  little  bird). — The  bird's- 
head  processes  of  the  Potyzoa. 

Bacillaria,  144  (Lat.  bacitlum,  a  little  staff). — A  genus  of 
Diatomaceae. 


INDEX    AND   GLOSSARY.  407 

Bacillus,  297,  327. — A  genus  of  Schizomycetous  Fungi. 

Bacterium,  135,  161,  315,  327  (Gr.   bacterion,  a   staff). — 
A  genus  of  Schizon^cetous  Fungi.     These  rodlike,  moving  ' 
filaments  have  been  referred  to  the  Algae  as  well  as  to  the 
animal  kingdom.    Their  nature  is  very  obscure.     See  p.  135. 

Balsam  (Canada),  Liquid  resin  of  Pinus  balsamea,  73. 

Balsam  cement,  76. 

Balsam  mounting,  79. 

Balanus,  174  (Gr.  balanos,  an  acorn). — The  acorn-shell, — a 
family  of  Cirrhipeda. 

Bathybius,  96,  158. — Gelatinous  matter  from  the  bed  of  the 
Atlantic  Ocean,  supposed  by  Huxley  to  be  of  the  family  of 
Rhizopods.  Its  animal  nature  is  disputed. 

Beale's  generalization  in  biology,  118. 

Beale  on  Inflammation,  248. 

Beale's  carmine  fluid,  69. 
"        injecting  fluids,  72. 
"        tint-glass  camera,  40. 

Beck's  microscope,  32. 

"       economic  microscope,  etc.,  345. 
"       iris  diaphragm,  33. 
"       illuminator,  38. 

Bedbug,  339. —  Cimex  Lectularius. 

Bell's  cement,  76. 

Beroe,  167. — Formerly  classed  among  the  cilograde  Acalephs, 
now  generally  in  the  class  (Ctenophora)  of  the  sub-kingdom 
Ccelenterata. 

Bergmehl,  94. — Mountain  flour.  A  powdery  mineral,  con- 
sisting largely  of  the  silicious  valves  of  Diatoms.  In  times  of 
scarcity  in  some  countries  it  is  mixed  with  food. 

Bile  in  urine,  303. 

Binocular  Microscope,  30  (Lat.  binus,  two  ;  oculus,  eye). 
"          Eye-piece,  30. 

Bichromate  of  Potash,  68. 

Bipinnaria,  168. — The  larval  form  of  the  star-fish,  named 
from  the  symmetry  of  its  swimming  organs.  The  star-fish  is 
developed  around  the  stomach  of  the  larva. 

Biology,  The  Microscope  in,  18, 116  (Gr.  bios,  life,  and  logos, 
discourse). 


408  INDEX    AND   GLOSSARY. 

Bioplasm — living  matter,  118,  122,  183. 
as  germs  of  disease,  339. 

Bismuth  test,  306. 

Blastema,  124  (Gr,  blastos,  a  bud). — A  term  given  by  the 
early  histologists  to  the  fluid  from  which  it  was  supposed  cells 
sprouted  spontaneously. 

Blastoderm,  201. — The  membrane  of  the  ovum  from  which 
all  the  tissues  sprout  or  originate. 

Blight,  136. — A  term  loosely  applied  to  a  variety  of  diseases 
in  plants,  as  well  as  to  the  causes  of  such  diseases,  as  insects 
(animal  blights)  and  parasitic  fungi. 

Bladder,  212. 

Blood,  186. 

Bloodvessels,  208. 

Blood  in  disease,  295. 

Blood-tests,  102,  105,  299. 

Bone,  91,  195. 

Boracic  acid,  68, 

Borax  and  carmine  fluid,  69. 

Botrytis,  18,  136. 

Bowman1  s  glands,  219. 

Brain  softening,  235. 

Branchia  (Gr.  bragchia,  the  gill  of  a  fish). — A  respiratory 
organ  adapted  to  breathe  air  dissolved  in  water. 

Brunswick  black,  76. 

Bread,  323. — Adulteration  of  flour  is  readily  determined, 
but  the  baking  of  bread  affects  the  form  of  the  starch-grains. 
Various  parasitic  fungi  and  their  spores  may  sometimes  be 
found  on  bread. 

Brunonian  movement,  53,  120. — Molecular  motion  of  parti- 
cles suspended  in  fluid. 

Bryozoa,  168  (Gr.  bruon,  moss  ;  zoon,  animal). 

Buds,  sections  of,  157. 

Bullseye  condenser,  36. 

Bunt,  136. 

Cabinet,  81. 

Calcium,  chloride  of,  75. 

Calyptra,  154. — The  hood  of  an  urn-moss. 


INDEX    AND   GLOSSARY.  409 

Cambium. — The  viscid  fluid  between  the  bark  and  wood  of 
Exogens,  when  new  wood  is  forming. 

Camera  lucida,  39. — Used  in  microscopy  for  drawing  the 
optical  image  produced  by  it. 

Calcification,  234,  241. — Infiltration  of  animal  tissues  with 
salts  of  lime. 

Camphor,  133. 

Canada  balsam,  73. 

Cancer,  288  (Lat.  cancer,  a  crab). — A  malignant  new  for- 
mation. 

Canaliculi  of  bone,  196. 

Capillaries,  201 — Minute  vessels  between  the  terminal  ar- 
teries and  veins. 

Carbolic  acid,  74. 

Carbo-hydrates,  184. 

Carmine  fluids,  69. — Carmine  is  a  pigment  made  from  cochi- 
neal. 

Cartilage,  195. 

Catarrh,  254  (Gr.  kata,  down,  and  rheo,  to  flow). 

Caseation,  233,  253. — Transformation  of  a  fatty  into  a  cheesy 
substance. 

Carbuncle,  298. 

Carbonate  of  lime,  99,  314. 

Caustic  potash,  67. 

Cauliflower  excrescence,  295. 

Cavernous  tumor,  270. 

Cavities  in  crystals,  89. 

Cells,  77  (Lat.  cellar,  a  little  chamber). 

Cell,  117,  118. — The  elementary  unit  of  organic  structure. 
"      structure,  119. 
"      genesis,  124. 
"      wall,  in  plants,  129. 

Cellulose,  67,  129. — The   proximate   principle   of  cell-mem- 
brane in  plants,  and  of  the  mantle  of  Tunicata. 

Cellular  plants,  134. 

Cements,  75. 

Cercomonas,  331  (Gr.  kerkos,  the   tail ;    monas,  unity. — A 
tailed  infusorial  monad. 


410  INDEX    AND    GLOSSARY. 

Cerebellum,  216. 

Cerebral  nerves,  216. 

Cesium  veneris,  167. 

Cephalopoda,  171  (Gr.  kephale,  head  ;  poda,  feet). 

Characese,  154. 

Chalk  strata,  95. 

Chemical  reagents,  67. 
"         teste,  106. 

products  of  decay,  231. 

Chloride  of  sodium,  68. 
"        "    gold,  70. 

Chlorophyll,  133  (Gr.  chloros,  green  ;  phyllos,  leaf ).— The 
green  coloring-matter  of  plants. 

Cholesterin,  233  (Gr.  cftofe,  bile,  and  stear,  suet). 

Chlorides  in  urine,  302,  314. 

Chromic  acid,  66,  67. 

Chloride  of  calcium,  75. 

Chorion,  204  (Gr.  chorion,  skin). 

C/M/fe,  190  (Gr.  chulos,  juice). 

Cicatricial  tissue,  262. 

CWi'a,  124,  191  (Lat.  cilium,  an  eyelash). — Minute,  hairlike 
bodies,  on  cells. 

Ciliograda,  167  (Lat.  cilium,  and  gradior,  I  walk). 

Ciliated  epithelium,  191. 

Cirrigrada,  167  (Lat.  cirrus,  a  curl  or  tendril). 

Cirrhipeds,  174  (Lat.  cirrus,  and  pes,  a  foot). 

Cirrhosis  of  Liver  (252). — Shrinking  of  the  liver. 

Circulation,  187. 

Classes  of  microscopes,  28. 

Ciliary  motion,  161,  170. 

Cleaning  covers,  77. 

Cleavage  of  yelk,  201. 

Cloudy  swelling,  244. 

Coa/,  92. 

Coccoliths,  96  (Gr.  kokkos,  a  berry  ;  lithos,  a  stone). 

Cochlea,  222  (Gr.  kochlos,  a  spiral  shell). 

Coddington  lens,  23,  82. 

Colors  of  flowers,  133. 

Coloring  matter,  184. 


INDEX    AND    GLOSSARY.  411 

Collomia  seeds,  130. 

Colloid  degeneration,  236  (Gr.  holla,  glue). 
"       tumors,  238. 
"  "       of  ovary,  239. 

"  cancer,  293. 
Compressorium,  41. 
Collinses  Harley  microscope,  32. 

"        graduating  diaphragm,  32. 
Compound  microscope,  23. 

"  crystals,  89. 

"          tissues,  197. 

"          eyes,  176. 
Condensers,  Achromatic,  33. 

"  Webster's,  34. 

"  Readers,  34. 

Condensing  lens,  37. 
Conifer  se,  131. 

Conidia,  137. — Reproductive  granules  of  fungi  and  lichens. 
Conjugation  of  cells,  140. 

"  in  infusoria,  162. 

Connective  tissues,  67,  192. 

Conchifera,  170  (Gr.  concha,  a  shell ;  /e-ro,  I  carry). 
Contagium  vivum,  339. 
Condensing  prism,  35,  347. 
Correlation  of  force,  117. 
Cornea,  220  (Lat.  cornu,  a  horn). 
Cora/,  164. 
Corpus  luteum,  215. 
Cbssus  ligniperda,  179. 
Corti's  organ,  223. 
Corns,  192,  286. 

Crinoids,  167  (Gr.  krinos,  a  lily;  etcfos,  form). 
Croupous  exudation,  257. 

"        pneumonia,  259. 
Cuttle-fish  bone,  170. 
Crystalline  forms,  86,  114. 
Crystallization,  100. 
Crystallography,  89. 
Crystalloid,  66. — Capable  of  crystallization. 


412  INDEX    AND    GLOSSARY. 

Cryptogamia,  152  (Gr.  kryptos,  hidden,  and  gamos,  marriage). 
— Plants  with  inconspicuous  sexual  organs. 

Crustacea,  IT 2. 

Cyclops,  173. 

Cypris,  173. 

Cystin,  314. 

Cryptococcus,  325. 

Cyclosis,  129. — Fluid  circulation  in  plant-cells. 

Dammar  mounting,  74,  79. 

Barker's  selenite  stage,  44. 

Dark-ground  illumination,  35. 

Daphnia,  173. — A  genus  of  microscopic  Crustaceans.  The 
water  flea. 

Deane's  compound,  74. 

Dead  cells,  229. 

"     cell-membrane,  230. 

Decapoda,  174  (Gr.  deka,  ten ;  poda,  feet). 

Decaying  protoplasm,  229. 
"        nerve,  230. 
"        fat-cells,  231. 
"         connective  tissue,  231. 
u        elastic  fibre,  231. 
"         cartilage,  231. 
"        force,  231. 

Decomposing  blood,  229. 

Degeneration  of  tissues,  232. 

Demodex  folliculorum,  179. 

Definition,  54. — Power  to  give  a  distinct  image. 

Dental  tissue,  192. 

Dentine,  196. 

Development  of  tissues,  201. 

Dentzia  scabra,  132. 

Development  of  fungi,  137. 

Desmidiaceae,  140. — A  family  of  Confervoid  Algae.  Micro- 
scopic fresh-water  organisms,  generally  green;  epidermis  not 
silicious,  as  is  the  case  with  Diatoms.  Reproduce  by  cell- 
division,  b}T  zoospores,  and  by  conjugation.  The  latter  form 
produces  a  sporangium,  which  is  sometimes  spiny,  and  has 
been  described  as  a  species  of  Xanthidium. 


INDEX   AND    GLOSSARY.  413 

Family  1.  Closterieae. — Cells  single,  elongated,  never  spi- 
nous,  frequently  not  constricted  in 'the  middle;  sporangia 
smooth. 

Gen. — Closterium.  Penium.  Tetmemorus,  Docidium. 
Spirotsenia. 

Family  2.  Cosmariese. — Cells  single,  constricted  in  the  mid- 
dle ;  sporangia  spinous  or  tuberculated. 

Gen. — Micrasterias.  Euastrum.  Cosmarium.  Xanthidium. 
Arthrodesmus.  Staurastrum.  Didymocladon. 

Family  3.  Desmidese. — Cells  united  into  a  filament ,  sporan- 
gia spherical,  smooth. 

Gen. — Hyalotheca.  Didymoprium.  Desmidium.  Aptogo- 
num.  Sphoerozosma. 

Family  4.  Ankistrodesmise. — Cells  elongated,  entire,  small, 
in  fagot-like  groups. 

Gen. — Ankistrodesmus. 

Family  5.  Pediastreze. — Cells  grouped  in  form  of  a  disk  or 
star,  or  side  by  side  in  one  or  two  short  rows. 

Gen. — Pediastrum.     Monactinus.     Scenedesmus. 

Diabetic  sugar,  305. 

Diagnosis,  microscope  in,  295. 

Diaphragm,  Rotary,  32. — An  instrument  for  intercepting 
excessive  rays  of  light. 

Diaphragm,  cylinder,  32. 

u  graduating,  33. 

"  iris,  33. 

Diatomaceae,  56,  94,  141. — A  family  of  Algae. 

Diffraction  of  Light,  54. — Disturbance  of  the  ray  by  the 
edge  of  an  opaque  body. 

Difflugia,  159. 

Diphtheritic  exudation,  260. 

Discrimination  of  blood,  299. 

Distomum,  335  (Gr.  dis^  double ;  stomata,  mouths). 

Disease  germs,  339. 

Dotted  cells,  130. 
"      ducts,  131. 

Double  Refraction,  91. — The  power  some  crystals  have  of 
exhibiting  two  images. 

Double  staining,  347. 


414  INDEX    AND   GLOSSARY. 

Duchenne^s  trocar,  234. 

Dytiscus,  177  (Or.  dytiskos,  diving). 

Ear,  222. 

Earths,  analysis  of,  99. 

Echinococcus,  171,  333  (Gr.  echinos,  a  hedgehog;  kokkus, 
a  berry). — Larval  forms  (scolices)  of  tapeworms,  known  as 
"  hydatids." 

Echinodermata,  167  (Gr.  echinos,  and  derma,  skin). — Spiny- 
skinned  animals. 

Ectosarc,  158  (Gr.  ektos,  outside ;  sarx,  flesh). 

Eczema,  256. — A  vesicular  eruption  on  the  skin. 

Eggs  of  Insects,  175. — These  are  interesting  microscopic  ob- 
jects from  the  variety  of  their  forms,  colors,  and  markings,  and 
the  singular  lids  of  many  of  them.  The  markings  are  analo- 
gous to  other  unicellular  organisms,  as  spores,  pollen  grains, 
Desmids,  and  Diatoms. 

Elastic  fibres,  194. 

Elaters,  154  (Gr.  elater,  an  impeller), — In  the  Equisetacese, 
elaters  are  four  elastic  filaments  attached  to  the  spore,  which, 
by  their  uncoiling,  jerk  the  spore  away  from  its  position.  They 
seem  to  be  formed  by  spiral  fissures  in  the  outer  coat  of  the 
spore.  In  liverworts  (Hepaticeae)  the}7  are  elastic  fibres  coiled 
in  membranous  tubes,  and  originate  as  spiral  fibres  of  vessels. 
They  are  supposed  to  assist  in  the  dispersion  of  spores. 

Elytra,  175  (Gr.  elution,  a  sheath). 

Electrical  cement,  76. 

Elephantiasis,  270. — A  species  of  leprosy  or  skin  disease. 

Embryology,  204  (Gr.  en,  in  ;  bruo,  I  swell). 

Embolism,  272. — Result  of  occluding  clots  in  bloodvessels. 

Embryonic  cells,  263. 

Enchondroma,  278. — Cartilaginous  tumor. 

Encephalon,  development  of,  203  (Gr.  egcephalos,  brain). 

Encephaloid  cancer,  292. 

Endochrome,  152. — Used  for  cell-contents  of  Algae. 

Endogenous  stems,  156  (Gr.  endon,  within  ;  gennao,  I  bring 
forth). 

Endosmose,  129  (Gr.  endon;  otheo,  I  push). — The  current 
flowing  inwards  when  diffusion  of  fluids  occurs  through  a 
membrane. 


INDEX    AND    GLOSSARY.  415 

Endothelium,  202  (Gr.  endon;  thallo,  I  bloom). 
Entomostraca,  173. — A  family  of  Crustacea. 
Entozoa,  171,  330  (Gr.  entos,  within,  and  zoon,  an  animal). 
Epiderm,  development  of,  203. 

Epithelium,  190  (Gr.  epi,  upon;   thallo,  I  bloom).  —  Cells 
covering  surfaces  of  animal  bodies. 
Epithelium  in  blood,  298. 
"          in  urine,  309. 
Epithelioma,  293. — A  species  of  cancer. 
Epizoa,  330. — Parasitic  animals. 
Eozoon,  84,  97  (Gr.  eos,  dawn ;  zoon,  animal), 
Enamel,  192,  197.— Covering  of  teeth. 
Equisetaceae,  155. — A  family  of  Cryptogams. 
Equisetum,  132 — A  genus  of  Equisetacese. 
Epiphytes,  324. — Parasitic  plants. 
Epiblast,  202. — Upper  layer  of  blastoderm. 
Errors  of  interpretation,  52. 
Ether,  68,  108. 
Eosin-staining,  348. 
Eolis,  127. 

Esophagus,  209  (Gr.  oisophagus,  the  throat). 
Examination  of  minerals,  85. 

"  of  higher  plants,  155. 

u  of  sputum,  316. 

"  of  the  air,  321. 

Excretions,  318. — Products  of  waste  or  decomposition   in- 
capable of  further  use  in  the  body. 
Exudation,  247,  253. 

"          corpuscles,  233. 

Exogenous  stems,  156  (Gr.  exo,  out,  and  gennao,  to  grow). — 
Dicotyledonous  plants. 
Eyes,  care  of,  49. 

"     of  insects,  176. 
Eye-pieces,  26. 
Eye-piece  micrometer,  38. 
Eye-glass,  23. 

tissue,  1 95. 
acids,  184. 
degeneration,  233. 


416  INDEX    AND    GLOSSARY. 

Fatty  infiltration,  243. 

"  "         of  liver,  244. 

False  membranes,  256. 

Fermentation,  135. 

"  test  for  sugar,  306. 

Feet  of  insects,  177. 

Ferns,  155,  349. 

Fehling's  test  for  sugar,  305. 

Fibres,  185. 

Fibrillar  connective,  194. 

Fibrin,  253,  270  (Lat.  ^6m,  a  fibre). 

Fibrinous  exudation,  256. 

Fibro-cartilage,  195. 

Fibroma,  267. — Connective  tissue  tumor. 
"        molluscum,  268. 

Field-glass,  23. 

Filaria  in  blood,  297,  337. 

Fission  of  cells,  125. 

Fixed  oil  in  plants,  133. 

Flannel,  Natural. — Interwoven  filaments  of  Confervae,  re- 
sembling coarse  cloth,  sometimes  found  in  summer  on  the 
margins  of  ponds. 

Flatness  of  field,  55. 

Flea,  339.  Pulex  Irritans. — The  last  segment  of  the  abdo- 
men of  the  female,  called  the  pygidium,  has  disklike  areolae, 
which  is  sometimes  used  as  a  test-object. 

Floscularia,  164. — A  genus  of  Rotatoria. 

Flint,  96. 

Fluid  media,  66. 
"     mounting,  80. 
"     cavities  in  minerals,  84,  89. 

Flowers,  157. 

Foraminifera,  95, 159. — Small  calcareous  shells  full  of  pores 
or  foramina* 

Formed  Material,  118. — Structure  produced  by  bioplasm. 

Fossil  plants,  ^3,  156. 

Food,  examination  of,  323. 

Freezing  specimens,  228. 
"        microtome,  228. 


INDEX    AND    GLOSSARY.  417 

Fraunhofer' 's  Lines,  44,  101. — Dark  lines  in  the  solar  spec- 
trum, seen  by  the  spectroscope. 

Frog-plate,  41.  —  The  common  frog  will  afford  means  of 
studying  several  kinds  of  structures.  By  scraping  the  roof  of 
the  mouth  with  a  scalpel,  ciliated  epithelium  may  be  obtained 
(page  191).  The  circulation  of  blood  may  be  seen  in  the  foot, 
mesentery,  lung,  tongue,  etc.,  by  inclosing  the  frog  in  a  wet 
bag  and  extending  the  tissue  over  the  aperture  in  the  frog- 
plate  (page  187).  The  ova  of  the  frog  are  frequently  used  in 
the  study  of  embryology,  and  the  transparent  parts  of  the 
tadpole  for  observing  the  development  of  the  tissues. 

Fungi,  18,  121,  134,  138,  232,  324. 
"        in  blood,  298. 
"        in  urine,  311. 

Galls. — Abnormal  growths  on  vegetables  produced  by  the 
sting  or  eggs  of  Hymenopterous  insects. 

Gammarus  pulex,  174,  320  (Gr.  gammarou,  a  lobster,  and 
Lat.  pulex,  a  flea). 

Ganglia,  200. — Nervous  knots. 

Ganglionic  Fibres,  199. — Remak's  fibres. 

Gas-chamber,  42. 

Gasteropoda,  170  (Gr.  gaster,  belly  ;  podes,  feet). — A  class  of 
Mollusca. 

Gelatinous  injections,  71. 

u  connective  tissue,  194. 

Generative  organs,  213. 

Generations,  alternation  of,  126. 

Germ-theory,  339. 

"  of  Dr.  Beale,  340.  < 

Germ-cell,  125. — Ovum. 

Germinal  Matter,  118,  122. — Another  name  for  bioplasm — 
living  protoplasm  or  "  cell-stuff." 

Germinal  vesicle,  201. 
"         spot,  201. 
"         plates,  202. 

Germ-fungi,  325. — Gymnomycetes. 

GerlacWs  carmine  injection,  72. 

Geology,  microscope  in,  92. 

Giant-cells,  265. 

27 


418  INDEX    AND    GLOSSARY. 

Glass-covers,  77. 
"      slides,  77. 
Glands  of  Brunner,  209. — Intestinal  glands. 

"         u    Lieberkuhn,  209. — Follicles  of  intestine. 
Glandular  Fibres,  131, — Woody  fibres  of  Coniferse. 

"          Tissue,  200.— Gland  structure. 

"          Epithelium,  191. — Lining  of  glands. 
Globules,  185. 

Glomeruli  of  kidneys,  212. — Arterial  tufts  of  Malpighi. 
Glioma,  277. — Tumor  of  nerve  connective  tissue. 
Globigerina,  96. — A  genus  of  Foraminifera. 
Glycerin,  74,  228.— The  sweet  principle  of  fats. 

"        and  gelatin,  74. 
. "        and  gum,  74. 

"        mounting,  80,  228. 
Goitre,  287. — Tumor  of  thyroid  gland. 
Goadby's  solution,  75.  » 

Gold  size,  75. 

Goniometer,  86. — An   instrument  for   measuring   angles  of 
crystals. 

Gonozooid,  166. — Sexual  zooid  of  Hydroids. 

Graduating  diaphragm,  33. 

Graafian  Follicles,  215.— Follicles  of  the  ovary. 

Granules,  185. 

Granulation,  262. — Mode  of  organization  after  suppuration. 

"  tissue,  262. 

Grammataphora  test,  57. 

Gregarinse,  330  (Lat.    gregarius,  in    flocks). — A  family  of 
parasitic  Protozoans. 

Gundlach's  objectives,  346. 

"  condenser,  347. 

Gum,  134. 

Gustatory  Cells,  218.— Elements  of  organs  of  taste. 
Guaiacum,  test  for  blood,  300. 
Hair,  191. 

"      of  insects,  175. 
"      worms,  172. 

Hardening  tissues,  62,  224,  227. 
Hartnach's  microscope,  32. 


INDEX    AND    GLOSSARY.  419 

Haustellum,  177  (Lat.  haustellum,  a  sucker). 

Hsematin,  103  (Gr.  haima,  blood). 

Heart,  208. 

"      i?i  insects,  178. 

Haversian  Canals,  196. — Vascular  canals  in  bone. 

Hepaticse,  154. — Liverworts  (Gr.  hepar,  the  liver). 

Hepatic  Lobules,  210. — Elemental  structures  of  the  liver. 

Herapathite,  113. — lododisulphate  of  quinia. 

Heterologous  Formation,  263. — A  tumor  differing  from  the 
tissue  it  is  found  in. 

HerscheVs  doublet,  22. 

High  powers,  55. 

Hipparchia  Janira,  56. — A  species  of  Lepidoptera. 

Histo-chemis  try,  185. 

Histology,  128,  182  (Gr.  histos,  tissue,  and  logos,  discourse). 
— The  science  of  tissues. 

Histological  preparations,  224. 

Holotliuride,  168  (Gr.  holos,  the  whole,  and  thura,  a  gate). — 
An  order  of  Echinodermata. 

Holland's  triplet,  23. 

Homologous  Formation,  263. — A  tumor  similar  to  the  tissue 
in  which  it  is  found. 

House-fly,  339. 

Huygenian  eye-piece,  26 

Hydroids,  165  (Gr.  hydor,  water,  and  eidos,  resemblance). — 
A  class  of  Co3lenterata. 

Hydrocyanic  acid,  test  for,  107. 

Hypersemia,  246  (Gr.  hyper,  excess  ;  haima,  the  blood). 

Hypoblast,  202. — The  lower  layer  of  the  blastoderm. 

Illumination,  22. 

Illuminators,  oblique,  34. 

11  dark-ground,  35. 

Indigo-carmine  fluid,  70. 

India-rubber,  133. 

Imbedding  tissues,  62,  227. 

Immersion  Lenses,  25, 51. — Objectives  requiring  fluid  between 
them  and  the  object. 

Improvements  in  microscopes,  345. 


420  INDEX    AND    GLOSSARY. 

Indifferent  Fluids,  61,  66.— Fluids  which  do  not  alter  the 
tissues. 

Indifferent  tissue,  264. 

Infusoria,  160  (Lat.  infusus,  infused). 
"         families  of,  163. 

Infusorial  earth,  94. 

Inflammation,  246. 

Inflammatory  Corpuscles,  233. — Fatty  degeneration  of  epi- 
thelium. 

Injecting,  64,  70. 

Insects,  174,  177. 

Intestinal  canal,  206. 
"         worms,  331. 
"         discharges,  318. 

Interpretation,  errors  of,  52. 

Inverted  microscope,  106. 

Invertebrata,  classes  of,  180. 

Involuntary  muscle,  197. 

lod-serum,  66. — Serum  and  iodine. 

Iris-diaphragm,  33. 

Ixodse,  338  (Gr.  ia?o,  to  adhere). 

Kellner's  eye-piece,  26,  33. 

Kidneys,  211, — Urinary  glands. 

Labyrinthodon,  97  (Gr.  labyrinth,  a  labyrinth,  and  odontes^ 
teeth). 

Labyrinth  of  Ear,  222. — Essential  part  of  organ,  consisting 
of  vestibule,  semicircular  canals,  and  cochlea. 

Lacunsb  of  Bone,  196. — Cavities  containing  bioplasts. 

Labium  of  Insects,  176. — Underlip. 

Lactification,  233. — The  last  act  of  fatty  degeneration. 

Lardaceous  Liver,  240. — Amyloid  infiltration. 

Lacticiferous  Vessels,  131. — Containing  milky  juice,  or  latex, 
of  plants. 

Lamps  for  microscopists,  50. 

Lawson's  dissecting  microscope,  60. 

Lasso-cells,  165. — Stinging  cells  of  Polyps. 

Leaves  of  plants,  157. 

Leech,  172,  337. — Hirudo  medicinalis. 

Leiomyoma,  266. — Tumor  of  unstriped  muscle. 


INDEX    AND    GLOSSARY.  421 

Lenses,  21. 

Lerncea,  113. — Parasitic  Crustacea. 

Leptothrix,  136,  260,  328. — A  fungus  found  on  epithelium, 
etc. 

Lepidocurtis,  56. — An  insect  similar  to  Podura. 

Lepra,  284. — A  peculiar  skin  disease. 

Leucocytes,  189  (Gr.  leukos,  white,  and  kytos,  a  cell). — White 
cells. 

Leucin,  232. — A  chemical  product  of  decay. 

Lepidoptera,  scales  of,  175. 

Leukaemia,    296.  —  Excessive    number    of    white    cells   in 
blood. 

Lieberkuhn,  37. 

Ligaments,  194. — Fibrous  tissues  connecting  bones. 

Light  for  microscope,  50. 

Life,  theories  of,  116. 

Living  Bodies,  Element  of,  117. — Bioplasm  or  cell. 

Litmus-paper,  107. 

Ligneous  Tissue,  130. — Sclerogen.     Woody  fibre, 

Lichens,  154. — An  order  of  Cryptogamous  plants. 

Liver,  210. — Largest  gland  connected  with  nutrition. 

Lignites,  93. — Fossils  of  vegetable  origin. 

Liverworts,  154. — Hepaticese. 

Ligula,  176. — Tongue  of  insects. 

Lice,  339. 

Lime  water,  68. 
"     salts,  115. 

Lipoma,  277. — Fatty  tumor. 

Liver-fluke,  335. — Distomum  hepaticum. 

Lister's  antiseptic  plan,  343. 

Locomotive  Organs,  215. — Bone,  muscle,  etc. 

Low  powers,  55. 

Logwood  staining  fluid,  70. 

Lungs,  213. — Organs  of  respiration. 

Lutein  Spectra,  105. — Spectra  from  juice  of  corpora  lutea  in 
the  ovary. 

Lupus,  283. — A  peculiar  skin  disease. 

Lymphatics,  207. — Yessels  of  the  lymph. 


422  INDEX    AND    GLOSSARY. 

Lymphatic  glands,  207. 
"  radicles,  207. 

Lymph,  189  (Lat.  a  stream).  ' 

Lymphoid  Organs,  208. — Having  structure  like  lymphatic 
glands. 

Lymphangioma,  270. — Tumor  of  lymphatic  vessels. 

Lymphoma,  272. — Adenoid  tumor. 

Magnesia  salts,  115. 

Maltwood's  finder,  48. 

Magnifying  power,  22,  40. 

Margarine,  232. 

Marine  glue,  76. 

Malignancy,  263. 

Malpighian  tufts  of  kidney,  212. 
"  vessels  of  insects,  178. 

Measuring  objects,  38. 

Medium  powers,  55. 

Metric  System,  38.  —  The  French  system  of  weights  and 
measures,  based  on  the  metre.  The  French  unit  of  weight  is 
the  gramme. 

Metamorphosis,  126. — Change  of  form. 

Mechanism  of  microscope,  27. 

Medusse,  167. — Jelly-fish. 

Melicertians,  164. — A  family  of  Rotifera. 

Membrane,  185. 

Medullary  Sheaths  of  Nerves,  199. — Sheath  of  axis. 

"          Eays,  156. — Cellular  plates  from  the  pith  to  the 
bark  in  exogenous  stems. 

Mesoblast,  202. — The  middle  layer  of  the  blastoderm. 

Medulla  Oblongata,  216.- — The  upper  part  of  spinal  cord, 
within  the  skull. 

Metallic  oxides,  tests  for,  110. 

Microscope,  compound,  23. 
"  testing  the,  54. 

Microspectroscope,  18,  44,  101. 

Micromineralogy,  84. 

Microchemistry,  98. 

Microchemical  analysis,  106. 
"  apparatus,  98. 


INDEX    AND    GLOSSARY.  428 

Microscopic  accessories,  32. 
"          slides,  77. 
"  lamp,  37,  50. 

"  table,  50. 

Micrometer,  38. 

Microgonidia,  152. — Bodies  resulting  from  segmentation  of 
motile  cells  in  cryptogams. 

Microcytes,  297. — Minute  cells. 

Microzymes,  135. — Minute  molecules  found  in  some  diseased 
products. 

Migration  of  cells,  189. 

Milk,  315. 

Mites,  178,  338.— A  famity  of  Arachnida. 

Micrococcus,  325. — Minute  vegetables,  sometimes  classed  as 
Algae. 

Microsporon   Audonini,  329.  —  Fungus   of    Porrigo   decal- 
vans. 

Microsporon  Furfur,  329. — Fungus  of  P^riasis. 

Miliary  tubercles,  274. 

Moist-chamber,  41. 

Holler's  test-plate,  57. 

Mounting  objects,  76,  79. 

Monera,  158. — A  term  given  to  the  simplest  forms  of  animal 
life. 

Mouths  of  insects,  176. 

Molecular  movement,  120. 

"          Coalescence,  128. — Action  of  chemical  substances 
on  colloids  in  a  nascent  state. 

Mosses,  154. 

Moschus  Javanicas,  187. — Musk  deer. 

Motions  of  objects,  53. 
"        of  cells,  120. 

Morbid  anatomy,  226. 

"       changes  in  inflammation*  246. 

Morphological  products,  183. 

Mould  diseases,  328. 

Mucus,  190,309,  314. 

Mucous  membrane,  206. 
"       exudation,  254. 


424  INDEX    AND    GLOSSARY. 

Mucoid  degeneration,  235. 

Mucous  polypi,  287. 

Mucin,  235. 

Mucor,  136,  325. — Mould-fungus. 

Muriatic  acid,  67. 

Mullens  eye  fluid,  68,  227. 

Muscardine,  18, 136. — A  fungous  disease  in  silkworms. 

Multipolar  nerve-cells,  199. — Cells  with  many  fibres. 

Muscle,  197. 

"       in  insects,  179. 
Muscular  tissue  growths,  266. 

Mycelia    of    Fungi,    135,     137. — Filaments  of    vegetative 
cells. 

Myelon,  203. — Spinal  cord. 
Myxoma,  268. — Gelatinous  tumor. 
Nachet's  inverted  microscope,  32. 

"        prism,  35. 

Nais,  172. — A  genus  of  Choetopodous  worms. 
Nails,  192. 

Ndevus,  269. — A  vascular  tumor. 
Naphtha  and  creasote,  74. 
Navicula  rhomboides,  56. 
Necrosis,  229.— The  death  of  tissue. 
Necrosed  muscle,  230. 

Nematoid  worms,  171  (Gr.  nema,  a  thread,  and  eidos,  form). 
Nerve  tissue,  198,  217. 
"     fibres,  199. 
"      cells,  199. 
"      preparations,  217. 
Neurilemma,  199. — Sheath  of  nerve-fibre. 
Neuroma,  266. — Tumor  on  nerve. 
Nicholas  prism,  43. 
Nitrogenous  substances,  67. 
Nitric  acid,  67. 
Nitrate  of  silver  fluid,  70,  108. 

"  "     -injection,  73. 

NoberVs  lines,  56. 

"        illuminator,  35. 
Nose-piece,  47. 


INDEX    AND   GLOSSARY.  42$ 

Nostochinse,  151,  322.— A  family  of  Confervoid  Algae. 

Notochord,  203. — The  gelatinous  column   forming  the  pri- 
mary state  of  spine  in  vertebrates. 

Nucleus  of  Cells,  119.— New  centres  of  living  matter. 

Nutritive  organs,  206. 

Numbering  blood-corpuscles,  296. 

Oberhauser's  drawing  apparatus,  39. 

Object  glasses,  25. 
"     finders,  48. 

Oblique  Illumination,  34. — Light  thrown  obliquety  through 
an  object. 

Ocular  micrometer,  38,  296. 

Ocelli,  176. — Facets  of  compound  eyes  of  insects. 

(Ecoid,  188. — A  constituent  of  the  red  blood-corpuscle. 

Octospores,    153. — Subdivisions    of    sporangia     in    certain 
Algae. 

Oidium  Albicans,  329. — Thrush-fungus. 

Oil  of  cloves,  68,  80. 

Oolites,  90. — Rocks  whose  structure  resembles  eggs  of  fish. 

Oospores,  152. — Reproductive  cells  of  Oscillatoria. 

Operculum,  154. — The  lid  of  spore-capsules  in  mosses,  etc. 

Opaque  injections,  65,  70. 
"       objects,  77. 

Orbitalites,  159. — Foraminiferous  shells  in  limestone. 

Organic  principles,  183. — Formative  materials. 

Organization  after  inflammation,  261. 

Organ  of  Corti,  223. — A  complicate  apparatus  in  the  inner 
ear. 

Organs  of  special  sense,  218. 

Origin  of  rocks,  92. 

Oscillatorise,  151. — A  family  of  Confervoid  Algae. 

Osmic  acid,  70. 

Osseous  tissue,  195. — Bone. 

Osteoblasts,  196. — Cells  developing  bone. 

Osteoma,  278. — An  osseous  tumor. 

Osteochondroma,  278. — An  ossifying  enchondroma. 

Ovum,  201 — Egg. 

Ovary,  214. — Essential  organ  of  reproduction  in  the  female. 

Ovipositors,  177. 


426  INDEX    AND   GLOSSARY. 

Oxalic  acid,  67. 

Oxalate  of  ammonia,  108. 
"        "    lime,  313. 

Pabulum,  118,  183. — Nutritive  material  of  cells. 

Pacinian  fluid,  75. 

"          corpuscles,  218. 

Papilloma,  285. — Papillary  tumor. 

Palaeontology,  97. — Science  of  fossils. 

Palmellacese,  139. — A  family  of  Confervoid  Algae. 

Palate  of  Molluscs,  171. — Tube  set  with  siliceous  teeth. 

Parasites,  324. — (Gr.  para,  by  the  side  of,  and  sitos,  nour- 
ishment), 

Paraphyses,  154. — Elongated  cells  in  spore-cases  of  lichens- 

Parasitic  Crustacea,  173. 

Parthenogenesis,  126. — Reproduction  without  sexual  union. 

Pathological  histology,  226. 
"  specimens,  227. 

"  new -formations,  262. 

Parabolic  illuminator,  36. 
"         speculum,  37. 

Pancreas,  210. — A  salivary  gland  of  the  intestines. 

Penetration,  55 — Exhibition  of  structure  below  the  focal 
layer. 

Periscopic  eye-piece,  26. 

Perforating  glass,  78. 

Penicillium,  136,  325. — A  species  of  mould-fungus. 

Peristome,  154. — Toothed  fringe  or  spore-capsule  of  mosses. 

Pernicious  anaemia,  297. 

Perivascular  Canals,  207. — Lymphatic  sheaths  of  vessels. 

Peyer's  Glands,  209. — Aggregations  of  glands  in  the  walls  of 
intestines. 

Pigmentation,  242. — Infiltration  of  pigment. 

Pigment  bodies,  232. 
"        in  lungs,  242. 
"        bacteria,  326. 

Pistillidia,  154. — Female  organs  of  mosses,  etc. 

Phosphates,  313. 

Photography,  microscopic,  48. 

Plant-sections,  153,  347. 


INDEX    AND   GLOSSARY.  427 

Phanerogamia,  155  (Gr.  phaneros,  visible,  and  gamos,  mar- 
riage). 

Physograda,  167. — An  order  of  Acalephs,  now  referred  to 
Hydroida. 

Physalia,  167. — Portuguese  man-of-war. — A  genus  of  Hy- 
droida. Sub-class,  Siphonaphora. 

Pleurosigma,  56. 

Polariscope,  42,  99. 

Polycystina,  95,  160, — An  order  of  Rhizopods. 

Polymorphism,  136,  324. — Various  forms  produced  by  the 
same  germ. 

Polyps,  164  (Gr.  polus,  many  ;  pous,  foot). 

Polyzoa,  168  (Gr.  polus,  many;  zoa,  animals). 

Polypary,  166. — The  arborescent  structure  or  Hydroids. 

Polypite,  166. — The  nutritive  zooid  or  compound. 

Polygastrica,  160  (Gr.  polus,  many  ;  gaster,  the  stomach). 

Pollen  in  air,  322. 

Porifera,  160. — Sponges. 

Porpita,  167. — A  genus  of  Hydroida. 

Pond-stick,  81. 

Podura  plumbea,  56,  175. — A  species  of  insects. 

Family  Podurellde. 

Order  Thysanura. 

Polishing-slate,  94. — Tripoli. 

Potato  disease,  136. — A  species  of  fungus. 

Powers  of  objectives,  55. 

Preparation  of  objects,  58,  61,  65,  84,  99,  156,  204,  277. 

Preservative  fluids,  73. 

Preserving  objects,  76. 

Primordial  Utricle,  129. — The  bioplasmic  layer  of  the  vege- 
table cell-wall. 

Protoplasm,  Il8,  128.—"  Physical  basis  of  life,"  or  the  ele- 
mentary cell-material. 

Progressive  force,  130 . 

Prothallium  of  Ferus,  126,  155. — An  intermediate  form  be- 
tween the  spore  and  the  plant. 

Protopliytes,  129. — Primitive  plants. 

Protozoa,  158. — Simplest  forms  of  animals. 

Professional  microscope,  345. 


428  INDEX    AND    GLOSSARY. 

Primitive  groove  of  ovum,  202, 
Pier o-car mine  fluid,  70. 
Prussian  blue  fluid,  70. 
Pneumonia,  259. — Inflammation  of  lung. 
Pus,  189,  248,  314. 
Pustules,  255. 

Pysemia,  272, — Pus  in  blood. 

Pulmonigrada,  166. — An  order  of  Acalephs,  now  generally 
referred  to  Discophora  (Hydroida). 

Eadiolaria,  158. — An  order  of  Rhizopods. 

Raphides,  132. — Crystals  in  vegetables. 

Readers  condenser,  34. 

Red  blood-corpuscles,  186. 

Reproduction,  125. — Multiplication  of  higher  forms  of  life. 

Resolution,  55. — Exhibition  of  minute  details. 

"  after  inflammation,  261. 

Resin,  133. 

Reticulated  Vessels,  131. — Irregular  deposit  on  walls  of  ducts. 
Respiratory  organs,  213. 
Retina,  221. 

Retrograde  metamorphosis,  127. 
Resting  stage  of  cells,  140. — See  still-cells. 
Receptacles  of  Algde,  153. — The  part  which  bears  reproduc- 
tive filaments. 

Reticularia,  158. — An  order  of  Rhizopods. 
Recurrent  fibroid  tumor,  279. 
Refractive  media,  53. 
Rhodospermex,  153. — Red  sea-weeds. 
Rhizopods,  158. — Root-footed  Protozoa. 
Rotatoria,  163. — Wheel  animalcules. 
Ringed  worms,  337. — Annelidse. 
Rhabdomyoma,  266, — Muscular  tumors. 
Rotifera,  160,  163.— Wheel  animalcules. 
Round  worms,  171,  336. 
Rust,  136. — A  species  of  fungus. 
Sarcode,  118. — A  synonym  for  protoplasm. 
Salivary  glands,  209. 

"  "      of  insects,  178. 

"      corpuscles,  189. 


INDEX    AND    GLOSSARY.  429 

Sarcoma,  279.— Fibro-plastic  tumor. 

Sarcina,   328. —  A   vegetable   organism   sometimes   classed 
among  Algae. 

Sarcoptes  Scabiei,  338.— Itch-insect. 

Sandhopper,  174. — An  amphipod  Crustacean. 

Sclerogen,  130. — Woody  tissue, 

Scales  of  Lepidoptera,  175. 

Section-cutter,  63. 

Sections  of  hard  tissues,  62. 

Secretory  Organs,  208. — Glands. 

Section  of  skin,  218. 
"      "   crystals,  100. 
"      "   embryo,  205. 
"      knife,  228. 

Sebaceous  Glands,  209. — Glands  of  skin  secreting  fatty  matter. 

Sea  nettles,  166.— Jelly-fish. 
"    slugs,  167. — Holothuria,  etc. 
"    urchins,  169. — Echinus,  etc. 

Serpula,  172. — A  genus  of  Annulata. 

Seise,  177. — Lancets  of  Diptera. 

Sensory  Organs,  218. — Organs  of  special  sense. 

Selenite  stage,  44. 

Seeds,  157. 

Serous  infiltration,  245. 
"      exudation,  253. 

Screw  bacteria,  327. 

Scolex  of  Tapeworm,  332. — The  head  set  free  from  the  csyt 
in  development. 

Scirrhus,  288. — Hard  cancer. 

Schacht's  staining  fluid,  68. 

Scalariform  Vessels,  155. — Vessels  of  ferns. 

Showers  of  Flesh  and   Blood,  322. — Gelatinous   masses,  of 
vegetable  origin. 

ShadbolVs  turntable,  78. 

Shell  structure,  170. 

Steel  Disk,  40. — A  substitute  for  the  camera  lucida. 

Spectra,  102. — Lines  or  bands  seen  with  the  spectroscope. 

Soil  and  water,  examination  of,  322. 

Somatopleure,  203. — Layers  of  the  embryo  which  form  the 
walls  of  chest  and  abdomen. 


430  INDEX    AND    GLOSSARY. 

Softening  of  brain,  235. 

Sort,  155. — Fructifying  spots  of  ferns. 

Soda,  115. 

Side  reflector,  37. 

Simple  microscope,  21. 

Smut,  136. — A  species  of  fungus. 

Sperm-cell,  125. — A  synonym  for  spermatozoid. 

Spectrum  Analysis.  101. — Analysis  by  means  of  the  spectro- 
scope. 

Spiral  Motion,  130. — From   progression  of  the   centripetal 
point  in  space. 

Spiral  Vessels,  131. — A  spiral  deposit  in  ducts  of  plants. 

Spot  lens,  36. 

Sphagnum,  155. — Bog-moss. 

Spherical  Aberration,  22. — Errors  in  lenses  from  spherical 
shape  of  surface. 

Splicer -oplea,  152. — A  species  of  Cryptogamous  plants. 

Sponges,  160. — Poriferous  Rhizopods.     Some  form  of  them 
a  sub-class,  Polystomata. 

Spontaneous    Generation,   125. — The  theory   of  life  without 
parentage. 

Spring  clips,  80. 

Spiders,  179. — Class  Arachnida. 

Spermatozoids,  201,  214,  311. — The  male   elements   of  im- 
pregnation. 

Splanchnopleure,  203. — An  embryonic  layer  forming  the  wall 
of  the  intestinal  canal. 

Sporangia,  154- — Spore-cases  of  Cryptogams. 

Spinal  cord,  216. 
"     nerves,  216. 

Splenic  fever,  297. 

Spirilla  297,  328.— Screw  bacteria. 

Sputum,  316. — Discharges  from  the  mouth. 

Specific  gravity  of  urine,  301. 

Stage  micrometer,  38. 

Staining  cells,  122. 
"         tissues,  63. 
"        fluids,  69. 

Starch,  132. 

Stems  of  plants,'  156. 


INDEX    AND   GLOSSARY.  431 

Still-cells,  140. — A  condition  of  cells  of  the  unicellular  Algse, 
distinguished  from  the  motile  state. 
Student's  microscopes,  28. 
Strieker's  gas-chamber,  41. 

Star-fish,  167. — Order  Asteroidea,     Class  Echinodermata. 
Stings,  177. 

Stemmata,  176. — Solitary  eyes  of  insects,  etc. 
Striped  Muscle,  198. — Voluntary  fibres. 
Stomata,  157. — Openings  in  epiderm  of  leaves. 
Squamous  Epithelium,  191. — Edges  of  cells  overlapping. 
Sublimation,  99. — Dry  evaporation  and  condensation. 
Surirella  Gemma,  56,  58. — A  test  Diatom. 
Suppuration,  262. — One  of  the  results  of  inflammation. 
Sugar  in  urine,  305. 

Sucker  Worms,  334. — Order  Trematodes.     Class  Yermas. 
Sweat  glands,  209. 

Sympathetic  Nerve,  215. — The  nerve  of  the  viscera  and  blood- 
vessels. 

Syphilitic  blood,  298. 

Syphiloma,  281. — A  tumor  of  s}^philitic  origin. 
Synovial  Fluid,  190. — Secretion  from  the  synovial  membrane 
of  joints. 

Table,  50. 

Tardigrada,  164. — Water-bears. 

Tapeworm,  171,  381. 

Tactile  Papillae,  218. — Organs  of  touch  in  the  skin. 

Tallow,  133. 

Tests,  microscopic,  54. 
"      micro-chemical,  106. 
"     for  alkalies,  108. 
"     for  acids,  109. 
"     foroxides,llO. 
"      for  blood,  102. 

Talitrus  Saltator,  174.— The  sandhopper. 

Teleology,  19. — Exhibition  of  evidences  of  design  in  nature. 

Teeth,  97,  196. 

Tetraspores,  153.— Quadruple  spores  of  Algse. 

Terebratula,  170.— A  genus  of  fossil  shell. 

Tessellated  Epithelium,  190. — The  cells  lying  edge  to  edge. 

Termination  of  nerves,  200. 


432  INDEX    AND    GLOSSARY. 

Thin  cells,  77. 

Thread-worms,  336. 

"      capsules,  165. — Netting  or  lasso-cells  of  polypi. 

Thecse,  155. — Capsules  inclosing  spores  of  ferns. 

Theories  of  life,  1 16. 

Thoracic  Duct,  208. — Reservoir  of  the  lymph. 

Thwaite's  fluid,  74. 

Thiersch's  carmine  fluid,  69. 
"  blue  injection,  72. 
"  red  "  72. 

Ticks,    179,   338.— Family  Ixodse.     Order   Acarinro.     Class 
Crustacea. 

Tissue  elements,  185. 

Torula,  135,  325.— The  "  yeast-plant  "  fungus. 

Tow-net,  82. 

T&nia,  171. — The  tapeworm,  called  also  Cestodes.     See  p. 
331. 

Transformation,  126,  264. — Variations  in  development. 

Transparent  injections,  72. 

Triple  phosphates,  232,  240,  313. 

Tradescantia,  129. — A  genus  of  Commebynacese,  known  as 
spider-worts. 

Trichomonas,  320. — A  genus  of  Infusoria. 

Tricophyton  Tonsurans,  328. — The  parasitic  fungus  of  syco- 
sis, etc. 

Trommels  Test,  305. — A  test  for  sugar  in  urine. 

Trichina  Spiralis,  171,  337. — A  species  of  Nematoid  worm. 

Tripoli,  94. — Polishing  slate  containing  Diatoms,  etc. 

Thrombosis,  270. — Coagula  of  blood  in  the  vessels. 

Turntable,  78. 

Tunicata,  169. — A  class  of  Mollusca. 

Tube  casts,  311. 

Tubercle,  234,  274,  276. 

Tubuli  Seminiferi,  214.— Tubules  of  the  testes. 

Turpentine,  68. 

Tyrosin,  232,  314. — A  chemical  product  of  decomposition. 

Uric  acid,  242,  312. 

Uredo,  136. — A  genus  of  fungi,  producing  rust,  etc. 

Urinary  deposits,  307. 
"        examination,  300. 


INDEX    AND    GLOSSARY.  433 

Urates,  313. 

Ureters,  212. 

Urea.,  301. 

Uriniferous  Tubes,  211. — Glandular  tubes  of  kidney. 

Unstriped  Muscle,  198. — Involuntary  fibres. 

Unipolar  Nerve-cell,  199. — Cells  with  one  fibre. 

Umbilical  Vesicle,  203. — An   appendage  of   the   vertebrate 
foetus. 

Ulvaceae,  151. — A  family  of  Confervoid  Algae. 

Varieties  of  bioplasm,  123. 

Vascular  tissue,  201. 

Valentin's  knife,  62. 

Vacuoles,  162. — Spaces  or  watery  vesicles  in  the  bodies  of 
Infusoria,  etc. 

Vaginal  Discharges,  319. 

Vernier,  43. — A  short  graduated  scale,  sliding  on  a  larger 
scale,  so  as  to  show  fractions  of  divisions. 

Vegetable  cells,  128,  134. 

Velella,  167. — A  genus  of  animals  now  referred  to  the  Hy- 
drozoa. 

Ventral  Laminse  of  Embryo,  203. — Parts  of  the  blastoderm  of 
the  ovum. 

Vegetative  Organs,  206. — Pertaining  to  nutrition,  etc. 

Vesicles,  254. — Products  of  inflammation  of  the  skin. 

Vibriones,  135. — See  Vibrio. 

Vinegar  Eels,  171. — A  kind  of  Nematoid  worms. 

Vine  Disease,  136. — A  species  of  fungus. 

Vtbrio,  327. — A  genus  of  filamentous  Bacteria. 

Vibracula,  169. — Appendages  of  Polyzoa,  from  which  vibra- 
tile  filaments  project. 

Vitellus,  201.— The  yolk  of  the  ovum. 

Vitelline  Membrane,  201. — The  membrane  surrounding  the 
yolk  in  the  ovum. 

Visual  organs,  219. 

Vitreous  humor,  220. 

Vorticella,  161. — A  genus  of  Infusoria.     Bell-shaped  animal- 
cules. 

Volatile  oil,  133, 

Volvox,  140. — A  genus  of  Confervoid  Algae. 

28 


434  INDEX    AND    GLOSSARY. 

Voluntary  muscle,  197. 

Vomited  matters,  31 7. 

Warm  stage,  42. 

Wandering-cells,  121,  247. — Leucocytes  which  traverse  the 
tissues. 

Water-bears,  164. — The  Tardigrada,  placed  by  some  in  the 
class  Arachnida. 

Water-fleasy  173. — Several  kinds  of  microscopic  Entomos- 
tracan  Crustaceans. 

Wax,  133. 

Water  woodlouse,  172. — An  Isopod  Crustacean. 

Warts,  192. 

Wenham's  prism,  30. 

11         reflex  prism,  347. 

Webster's  condenser,  34. 

White  blood-cells,  188. 
"      varnish,  76, 

Woolaston  doublet,  23. 

Working  distance,  51. 

Woodward's  prism,  347. 

Xanthidia,  96. — Sporanges  of  Desmidiaceae  found  in  flint. 

Xanthoma,  277. 

Yeast-cells,  136. — The  Torula  or  yeast  fungus. 

FeZ/ow  tubercle,  274. 
"       elastic  fibre,  194. 

F0/A-,  201. — Contents  of  the  vitelline  membrane  of  the 
ovum. 

Zentmayer's  microscope,  30, 

"  Centennial  microscope,  345. 

"  histological        "  345. 

Zooid,  188. — One  of  the  constituents  of  the  red  blood-disk. 

Zoea,  174. — The  larval  form  of  the  crab. 

Zoospores,  140.— Ciliated  cells  of  Algae,  etc.,  produced  by 
segmentation,  and  producing  new  individuals  after  being  en- 
cysted. 

Zoology,  microscope  in,  158. 

Zoophytes,  161. — Animal  flowers.  A  name  formerly  given 
to  Actinea  and  other  Hydroids. 

Zygnema,  151. — A  genus  of  Confervoid  Algae. 


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100  "2vo.s.  6  "      -        .        .        .        .        3.00 


INTERLEAVED   EDITION. 

For  25  Patients  weekly,  interleaved,  tucks,  pockets,  etc.,     .        ...        .        .        1.25 

50          "  "  "  "'  "          "       .        .        .        .        .        1.50 

50  «2vol, 

This  Visiting  List,  now  in  its  twenty-ninth  year,  contains  the  Metric  or  French  Decimal  System  of 
Weights  and  Measures,  a  Posological  Table  with  the  Doses  in  both  the  Apothecaries'  and  Decimal 
Metric  System  of  Weights  and  Measures,  a  new  Table  of  Poisons,  etc. 

PIGGOTT  (A.  SNOWDBN),  M.D. 

Copper  Mining  and  Copper  Ore.    With  a  full  Description  of  the 
Principal  Copper  Mines  of  the  United  States,  the  Art  of  Mining,  etc.     Price  1.00 

POWER,  HOLMES,  ANSTIE,  AND  BARNES. 

Reports  on  the  Progress  of  Medicine,  Surgery,  Physiology, 
Midwifery,  Diseases  of  Women  and  Children.       Price  2.00 

PRINCE  (DAVID),  M.D. 

Plastic  and  Orthopedic  Surgery.  Containing  a  Keport  on  the  Con- 
dition of,  and  Advance  made  in,  Plastic  and  Orthopedic  Surgery,  etc.,  etc.,  and 
numerous  Illustrations.  Price  4.50 

RADCLIPPE  (CHARLES  BLAND),  M.D. 

On   Epilepsy,  Pain,  Paralysis,  and  other  Disorders  of  the  Nervous 
System.     With  Illustrations.  Price  1.50 

REESE  (JOHN  J.),  M.D. 

Analysis  of  Physiology.     A  Condensed  View  of  the  most  important  Facts 
and  Doctrines  for  Students.     Second  Edition,  Enlarged.  Price  1.50 

REESE  (JOHN  J.),  M.D. 

The  American  Medical  Formulary.  Price  1.50 

REESE  (JOHN  J.),  M.D. 

A  Syllabus  of  Medical  Chemistry.  Price  1.00 

REYNOLDS  (J.  RUSSELL),  M.D.,  P.R.S. 

Lectures  on  the  Clinical  Uses  of  Electricity.     Second  Edition. 

Price  1.00 
RICHARDSON  (JOSEPH),  D.D.S. 

A  Practical  Treatise  on  Mechanical  Dentistry.     Third  Edition, 
much  Enlarged.     With  over  150  Illustrations.     Octavo.  Preparing. 


10  LINDSAY  &  BLAKISTON'S 

RIGBY  AND  MEADOWS. 

Obstetric  Memoranda.  Fourth  Edition,  Revised  and  Enlarged,  by 
ALFRED  MEADOWS,  M.D.  Price  .50 

RINDFLEISCH  (DR.  EDWARD). 

Text-Book  of  Pathological  History.  Translated  from  the  German, 
by  WM.  C.  KOLMAN,  M.D.,  assisted  by  F.  T.  MILES,  M.D.  208  Microscopical 
Illustrations.  Octavo.  Price,  bound  in  cloth,  5.00 ;  in  leather,  6.00 

ROBERTS  (FREDERICK  T.),  M.D.,  B.Sc. 

The  Theory  and  Practice  of  Medicine.  Third  American,  from 
Fourth  London  Edition.  Revised  and  Enlarged.  With  Illustrations. 

Price,  cloth,  5.00;  leather,  6.00 
ROBERTS  (D.  LLOYD),  M.D. 

The  Student's  Guide  to  the  Practice  of  Midwifery.  With  95 
Illustrations.  Price  2.00 

RYAN  (MICHAEL),  M.D. 

Philosophy  of  Marriage,  in  its  Social,  Moral,  and  Physical  Relations; 
the  Diseases  of  the  Genito-Urinary  Organs,  etc.  .  Price  1 .00 

SANDERSON,  KLEIN,  FOSTER,  AND  BRUNTON. 

A  Hand-Book  for  the  Physiological  Laboratory.  Being 
Practical  Exercises  for  Students  in  Physiology  and  Histology.  With  over 
350  Illustrations,  appropriate  letter-press  explanations  and  references  to  the 
text.  2  vols.,  cloth,  $7.00.  Price,  in  one  vol.,  cloth,  6.00;  in  leather,  7.00. 

SANSOM  (ARTHUR  ERNEST),  M.B. 

Chloroform.     Its  Action  and  Administration.  Price  1.50 

SEWILL  (H.  E.),  M.R.C.S.,  Eng.,  L.D.S. 

The  Student's  Guide  to  Dental  Anatomy  and  Surgery. 
With  77  Illustrations.  Price  1.50 

SMITH  (HEYWOOD),  M.D. 

Practical  Gynaecology.  A  Hand-Book  for  Students  and  Practitioners. 
With  Illustrations.  Price  1.50 

STILLE  (ALFRED),  M.D. 

Epidemic  Meningitis  ;  or,  Cerebro-spinal  Meningitis.  Price  2.00 

STOKES  (WILLIAM). 

The  Diseases  of  the  Heart  and  the  Aorta.     Octavo.         Price  3.00 

SWAIN  (WILLIAM  PAUL),  F.R.C.S. 

Surgical  Emergencies:  Containing  Concise  Descriptions  of  Various 
Accidents  and  Emergencies,  with  Directions  for  their  Immediate  Treatment. 
With  Illustrations.  Price  2.00 

SWERINGEN  (HIRAM  V.),  D.D. 

A  Pharmaceutical  Lexicon;  or,  Dictionary  of  Pharmaceutical  Science. 
Containing  explanations  of  the  various  subjects  and  terms  of  Pharmacy,  with 
appropriate  selections  from  the  collateral  sciences.  Formulae  for  officinal,  em- 
pirical, and  dietetic  preparations,  etc.,  etc.  Price,  in  cloth,  3.00;  in  leather,  4.00 


MEDICAL  PUBLICATIONS.  11 


TAPT  (JONATHAN),  D.D.S. 

A  Practical  Treatise  on  Operative  Dentistry.  Third  Edition, 
thoroughly  Revised,  with  Additions.  Over  100  Illustrations.  Octavo. 

Price,  in  cloth,  4.25 ;  in  leather,  5.00 

TANNER  (THOMAS  HAWKES),  M.D.,  P.R.C.P.,  etc. 

The  Practice  of  Medicine.  Sixth  American  Edition.  Kevised  and 
Enlarged.  With  extensive  Formulae  for  Medicines,  Baths,  etc.,  etc.  Royal 
Octavo  ;  over  1100  pages.  Price,  in  cloth,  6.00 ;  leather,  7.00 

TANNER  (THOMAS  HAWKES),  M.D.,  P.R.C.P.,  etc. 

Index  of  Diseases  and  their  Treatment.  Second  Edition. 
Carefully  Revised.  With  many  Additions  and  Improvements.  By  W.  H. 
BROADBENT,  M.D.,  F.E.C.P.  Octavo.  Cloth.  Price  3.00 

TANNER  (THOMAS  HAWKES),  M.D.,  P.R.C.P.,  etc. 

A  Practical  Treatise  on  the  Diseases  of  Infancy  and  Child- 
hood. Third  Edition,  Kevised  and  Enlarged.  By  ALFRED  MEADOWS, 
M.D.  Price  3.00 

TANNER  (THOMAS  HAWKES),  M.D.,  P.R.C.P.,  etc. 

A  Memoranda  of  Poisons.     Fourth  Edition,  much  Enlarged.    Price  .75 

TIBBETS  (HERBERT),  M.D. 

A    Hand-Book   of  Medical    Electricity.     Sixty-four    Illustrations. 

Price  1.50 
TOLAND  (H.  H.),  M.D. 

Lectures  on  Practical  Surgery.  Second  Edition.  With  Additions 
and  numerous  Illustrations.  Price,  in  cloth,  4.50 ;  in  leather,  5.00 

TRANSACTIONS    OP    THE   COLLEGE  OP    PHYSICIANS    OP 

PHILADELPHIA. 
New  Series,  Vols.  I,  II,  III,  and  IV.  Price,  per  volume,  2.50 

TROUSSEAU  (A). 

Lectures  on  Clinical  Medicine.  Delivered  at  the  H6tel  Dieu,  Paris. 
Translated  from  the  Third  Revised  and  Enlarged  Edition  by  P.  VICTOR 
BAZIRE,  M.D.,  and  JOHN  EOSE  CORMACK,  M.D.  With  Index,  Table  of 
Contents,  etc.  Complete  in  Two  Volumes,  royal  octavo. 

Price,  bound  in  cloth,  8.00  ;  in  leather,  10.00 

TROUSSEAU  (A). 

Sydenham  Society's  Edition,  5  Volumes. 

Volumes  I,  II,  and  III,  4.00  each  ;  Volumes  IV  and  V,  3.00  each. 

TYSON  (JAMES),  M.D. 

The  Cell  Doctrine.  Its  History  and  Present  State,  with  a  Copious  Bib- 
liography of  the  Subject.  With  Colored  Plate,  and  numerous  other  Illustra- 
tions. Second  Edition.  Price  2.00 

TYSON  (JAMES),  M.D. 

A   Practical   Guide   to   the  Examination   of  Urine.    For  the 

Use  of  Physicians  and  Students.  With  a  Colored  Plate  and  numerous  other 

Illustrations.     Third  Edition.  Price  1.50 


12  LINDSAY  &  BLAKISTON'S 


TURNBULL  (LAURENCE),  M.D. 

The  Advantages  and  Accidents  of  Artificial  Anaesthesia. 
A  Manual  of  Anaesthetic  Agents,  Modes  of  Administration,  etc,  Second 
Edition,  Enlarged.  25  Illustrations.  Cloth.  Price  1.50 

WALKER  (ALEXANDER),  M.D. 

Intermarriage  ;  or,  the  Mode  in  which,  and  the  Causes  why,  Beauty,  Health 
and  Intellect  result  from  certain  Unions ;  and  Deformity,  Disease  and  Insanity 
from  others.  With  Illustrations..  12 mo.  Price  1.00 

WARING  (EDWARD  JOHN),  P.R.C.S.,  etc. 

Practical  Therapeutics.  Considered  chiefly  with  reference  to  Articles 
of  the  Materia  Medica.  Third  American,  from  the  last  London  Edition. 

Price,  in  cloth,  4.00 ;  leather,  5.00 

WEDL  (CARL),  M.D. 

Dental  Pathology.  With  Special  Eeference  to  the  Anatomy  and  Physi- 
ology of  the  teeth,  and  notes  by  THOS.  B.  HITCHCOCK,  M.D.,  Prof,  of  Dental 
Pathology,  Harvard  University.  105  Illustrations. 

Price,  cloth,  3.50  ;  leather,  4.50 
WHEELER  (C.  GILBERT),  M.D. 

Medical  Chemistry  :  Including  the  Outlines  of  Organic  and  Physiological 
Chemistry,  Second  Edition.  Cloth.  Price  3.00 

WILSON  (JOSEPH),  M.D. 

Naval  Hygiene;  or,  Human  Health  and  means  of  Preventing  Disease, 
With  Illustrative  Incidents  derived  from  Naval  Experience.  Illustrations, 
etc.  Second  Edition.  Price  3.00 

WOODMAN  AND  TIDY. 

A  Text-Book  of  Forensic  Medicine  and  Toxicology.  By 
W.  BATHURST  WOODMAN,  M.D.,  Assistant  Physician  and  Lecturer  on  Physi- 
ology, London  Hospital ;  and  C.  MEYMOTT  TIDY,  M.A.,  M.B.,  Lecturer  on 
Chemistry,  and  Professor  of  Medical  Jurisprudence,  London  Hospital.  Nu- 
merous Illustrations.  Price,  cloth,  7.50 ;  leather,  8.50 

WYTHE  (JOSEPH  H.),  A.M.,  M.D. 

The  Physician's  Pocket  Dose  and  Symptom  Book.  Contain- 
ing the  Doses  and  Uses  of  all  the  Principal  Articles  of  the  Materia  Medica,  and 
Original  Preparations.  Eleventh  Revised  Edition. 

Price,  in  cloth,  1.00;  in  leather,  tucks,  with  pockets,  1.25 

WYTHE  (JOSEPH  H.),  A.M.,  M.D. 

The  Mieroseopist:  A  Manual  of  Microscopy  and  Compendium  of  the 
Microscopic  Sciences,  Micro-Mineralogy,  Micro-Chemistry,  Biology,  Histology, 
and  Practical  Medicine.  Fourth  Edition,  252  Illustrations.  Nearly  ready. 

OVERMAN  (FREDERICK),  M.S. 

Practical  Minerology,  Assaying,  Mining.     Tenth  PJditon. 

Cloth,  1.00 

MATTHIAS  (BENJAMIN),  A.M. 

A    Manual   for  conducting   Business   in  Town   and  Ward 
Meetings.     Sixteenth  Edition.  Cloth,  price,  50 


MEDICAL  PUBLICATIONS.  13 


MEDICAL    TEXT-BOOKS 

PUBLISHED    BY 

LINDSAY  &  BLAKISTON,   PHILADELPHIA, 


Robert's  Hand-Book  of  the  Practice  o'f  Medicine.  Octavo.  Price,  bound  in 
cloth,  $5.00  ;  leather,  $6.00. 

Trousseau's  Clinical  Medicine.  Complete  in  two  volumes.  Octavo.  Price,  in 
cloth,  $8.00  ;  leather,  $10.00. 

Aitken's  Science  and  Practice  of  Medicine.  Third  American,  from  the  Sixth 
London  Edition.  Two  volumes,  royal  octavo.  Price,  in  cloth,  $12.00 ;  leather,  $14.00. 

Sanderson's  Hand-Book  for  the  Physiological  Laboratory.  Exercises  for 
Students  in  Physiology  and  Histology.  353  Illustrations.  Price,  in  one  volume, 
cloth,  $6.00 ;  leather,  $7.00. 

Cazeaux's  Text-Book  of  Obstetrics.  From  the  Seventh  French  Edition,  Revised 
and  greatly  Enlarged.  With  Illustrations.  Cloth,  $6.00  ;  leather,  $7.00. 

Waring's  Practical  Therapeutics.  From  the  Third  London  Edition.  Cloth,  $4.00; 
leather,  $5.00. 

Rindfleisch's  Pathological  Histology.  Containing  208  elaborately  executed 
Microscopical  Illustrations.  Cloth,  $5.00;  leather,  $6.00. 

Meigs  and  Pepper's  Practical  Treatise  on  the  Diseases  of  Children.  Sixth 
Edition.  Cloth,  $6.00  ;  leather,  $7.00. 

Tanner's  Practice  of  Medicine.  The  Sixth  American  Edition,  Ee vised  and  En- 
larged. Cloth,  $6.00 ;  leather,  $7.00. 

Tanner  &  Meadow's  Diseases  of  Infancy  and  Childhood.  Third  Edition. 
Cloth,  $3.00. 

Biddle's  Materia  Medica  for  Students.  The  Eighth  Revised  and  Enlarged 
Edition.  With  Illustrations.  Price,  $4.00. 

Harris's  Principles  and  Practice  of  Dentistry.  The  Tenth  Revised  and  Enlarged 
Edition.  Cloth,  $6.50  ;  leather,  $7.50. 

Woodman  and  Tidy's  Forensic  Medicine  and  Toxicology,  Illustrated.  8vo. 
Cloth,  $7.50;  sheep,  $8.50. 

Byford  on  the  Uterus.  A  New,  Enlarged,  and  thoroughly  Revised  Edition.  Nu- 
merous Illustrations.  Price,  $2.50. 

Hewitt's  Diagnosis  and  Treatment  of  the  Diseases  of  Women.  Third  Edition. 
Cloth,  $4.00  ;  leather,  $5.00. 

Headland  on  the  Action  of  Medicines.     Sixth  American  Edition.     Price,  $3.00. 

Atthill's  Diseases  of  Women.  Fifth  Edition.  Numerous  Illustrations.  Price, 
$2.25. 

Meadow's  Manual  of  Midwifery.  Illustrated.  Third  Enlarged  Edition,  includ- 
ing the  Signs  and  Symptoms  of  Pregnancy,  etc.  Price,  $3.00. 

Fothergill's  Complete  Manual  of  the  Diseases  of  the  Heart,  and  their  Treat- 
ment. Second  Edition.  Price,  $3.50. 

Bioxam's  Laboratory  Teaching.     Fourth  Edition.     89  Illustrations.     Price,  $1.75. 

Taft's    Operative    Dentistry.      Third   Edition.     100   Illustrations.     Cloth.     Price, 

$4.25. 
Sweringen's  Dictionary  of  Pharmaceutical  Science.     Octavo.     Price,  $3.00. 

Tanner's  Index  of  Diseases,  and  their  Treatment.     A  New  Edition.     Price,  $3.00. 
Charteris1  Hand-Book  of  Practice.     Illustrated.     Price,  $2.00. 
Fenwick's  Outlines  of  the  Practice  of  Medicine.     With  special  reference  to  the 
Prognosis  and  Treatment  of  Disease.    With  Formula  and  Illustrations.     Large  12mo. 
Price,  $2.00. 


14  LINDSAY  &  BLAKISTON'S 


ROBERTS'  TEXTBOOK  of  He  THEORY  and  PRACTICE  of  MEDICINE. 

THIRD  AMEKICAN,  FEOM  THE  FOURTH  LONDON  EDITION. 
ONE  VOL.UME,  OCTAVO. 

Price,  bound  in  Cloth,  $5.00.    In  Leather,  $6.00. 

The  unexceptional  large  and  rapid  sale  of  this  book,  and  the  universal  com- 
mendation it  has  received  from  the  profession,  seems  to  be  a  sufficient  guaran- 
tee of  its  merit  as  a  Textbook.  The  publishers  are  in  receipt  of  numerous 
letters  from  Professors  in  the  medical  schools,  speaking  favorably  of  it,  and 
below  they  give  extracts  from  the  medical  press,  American  and  English, 
attesting  its  superiority  and  value  to  both  student  and  practitioner.  The 
present  edition  has  been  thoroughly  revised  and  much  of  it  re-written. 

"  The  best  Textbook  for  Students  in  the  English  language.  We  know  of  no  work  in  the  English 
language,  or  in  any  other,  which  competes  with  this  one." — Edinburgh  Medical  Journal. 

"  It  is  a  remarkable  evidence  of  industry,  experience,  and  research." — Practitioner. 

"  Dr.  Roberts'  book  is  admirably  fitted  to  supply  the  want  of  a  good  handbook,  so  much  felt 
by  every  medical  student." — Student's  Journal  and  Hospital  Gazette. 

"It  contains  a  va'stdeal  of  capital  instruction  for  the  student." — Medical  Times  and  Gazette. 

"  There  are  great  excellencies  in  this  book,  which  will  make  it  a  favorite  with  the  student." — 
Richmond  and  Louisville  Journal. 

"  To  the  student  it  will  be  a  gift  of  priceless  value." — Detroit  Review  of  Medicine. 

"  We  heartily  recommend  it  to  students,  teachers,  and  practitioners." — Boston  Medical  and 
/Surgical  Journal. 

"  It  is  of  a  much  higher  order  than  the  usual  compilations  and  abstracts  placed  in  the  hands 
of  students." — Medical  and  Surgical  Reporter. 

"  It  is  unsurpassed  by  any  work  that  has  fallen  into  our  hands  as  a  compendium  for  students." — 
The  Clinic. 

"  We  particularly  commend  it  to  students  about  to  enter  upon  the  practice  of  their  profes- 
sion."— St.  Louis  Medical  and  Surgical  Journal. 


SECOND  EDITION,  ENTIRELY  RE-WRITTEN. 


WITH  THEIR  TREATMENT;  INCLUDING  THE  GOUTY  HEART. 

By  J.  MILNER  POTHERGILL,  M.D., 

Author  of  "  The  Practitioner's  Handbook  of  Treatment,"  "The  Antagonism  of  Therapeutic  Agents,"  etxj. 
OCTAVO.    PRICE,  $3.50. 

"  It  is  the  best,  as  well  as  the  most  recent  work  on  the  subject  in  the  English  language." — 
Medical  Press  and  Circular. 

"  To  many  an  earnest  student  it  will  prove  a  light  in  darkness ;  to  many  a  practitioner  cast 
down  with  a  sense  of  his  powerlessness  to  cope  with  the  rout  and  demoralization  of  Nature's 
forces,  a  present  help  in  time  of  trouble." — Philadelphia  Medical  Times. 

"The  work  throughout  is  a  masterpiece  of  graphic,  lucid  writing,  full  of  good  sound  teaching, 
which  will  be  appreciated  alike  by  the  practitioner  and  the  student." — Student's  Journal. 

"  Dr.  Fothergill's  intention  has  rather  been  to  present  the  natural  history  of  heart  disease  as  a 
series  of  vivid  pictures  before  the  imagination  of  the  reader,  and  to  carry  the  doctor  as  a  living 
actor  into  the  scene.  For  this  purpose  he  has  properly  chosen  to  use  academic  detail,  not  ex- 
haustively, but  as  a  means  to  this  end,  and  he  has  brilliantly  succeeded." — Westminster  Review. 

"  The  most  interesting  chapter  is  undoubtedly  that  on  the  gouty  heart,  a  subject  which  Dr. 
Fothergill  has  specially  studied,  and  on  which  he  entertains  views  such  as  are  likely,  we  think,  to 
be  generally  accepted  by  clinical  physicians,  although  they  have  not  before  been  stated,  so  far  as 
we  are  aware,  with  the  same  breadth  of  view  and  extended  illustration." — British  Med.  Journal. 

"  Dr.  Fothergill's  remarks  on  rest,  on  proper  blood  nutrition  in  heart  disease,  on  the  treat- 
ment of  the  sequelae  of  it,  and  on  the  actions  of  special  medicine,  all  indicate  that,  in  studying 
the  pathology  of  heart  disease,  he  has  earnestly  kept  in  view  the  best  means  of  mitigating  suf- 
fering and  of  prolonging  life." — The  Lancet. 


MEDICAL  PUBLICATIONS.  15 

AMERICAN  HEALTH  PRIMERS. 

Edited  by  W,  W,  KEEN,  M,D,, 

Fellow  of  the  College  of  Physicians  of  Philadelphia ;  Surgeon  to 
St.  Mary's  Hospital,  etc. 


This  series  of  American  Health  Primers  is  prepared  to  diffuse  as  widely  and  cheaply  as  possible, 
among  all  classes,  a  knowledge  of  the  elementary  facts  of  Preventive  Medicine,  and  the  bearings  and 
applications  of  the  latest  and  best  researches  in  every  branch  of  Medical  and  Hygienic  Science.  They 
are  not  intended  (save  incidentally)  to  assist  in  curing  disease,  but  to  teach  people  how  to  take  care  of 
themselves,  their  children,  pupils,  employees,  etc. 

They  are  written  from  an  American  standpoint,  with  especial  reference  to  our  Climate,  Sanitary 
Legislation,  and  Modes  of  Life;  and  in  these  respects  we  differ  materially  from  other  nations. 

The  subjects  selected  are  of  vital  and  practical  importance  in  every -day  life,  and  are  treated  in  as 
popular  a  style  as  is  consistent  with  their  nature.  Each  volume,  when  the  subject  calls  for  it,  is  fully 
illustrated,  so  that  the  text  may  be  clearly  and  readily  understood  by  any  one  heretofore  entirely 
ignorant  of  the  structure  and  functions  of  the  body.  The  object  being  to  furnish  the  general  or  un- 
scientific reader,  in  a  compact  form  and  at  a  low  price,  reliable  guides  for  the  prevention  of  disease  and 
the  preservation  of  both  body  and  mind  in  a  healthy  state. 

The  authors  have  been  selected  with  great  care,  and  on  account  of  special  fitness,  each  for  his  subject, 
by  reason  of  its  previous  careful  study,  either  privately  or  as  public  teachers. 

Dr.  Keen  has  supervised  the  Series,  as  Editor;  but  is  not  responsible  for  the  statements  or  opinions 
of  the  individual  authors. 


I.  Hearing,  and  How  to  Keep  It.      With  Illustrations.      By 

CHAS.  H.  BURNETT,  M.  D.,  of  Philadelphia,  Consulting  Aurist  to  the 
Pennsylvania  Institution  for  the  Deaf  and  Dumb,  Aurist  to  the  Presby- 
terian Hospital,  etc. 

II.  Long  Life,  and  How  to  JReach  It.    By  J.  G.  RICHARDSON, 

M.  D.,  of  Philadelphia,  Professor  of  Hygiene  in  the  University  of 
Pennsylvania,  etc. 

III.  The  Summer  and  its  Diseases.    By  JAMES  C.  WILSON, 

M.  D.,  of  Philadelphia,  Lecturer  on  Physical  Diagnosis  in  Jefferson 
Medical  College,  etc. 

IV.  Eyesight,  and  How  to  Care  for  It.    With  Illustrations.    By 

GEORGE  C.  HARLAN,  M.  D.,  of  Philadelphia,  Surgeon  to  the  Wills  (Eye) 
Hospital. 

V.  The  Throat  and  the  Voice.    With  Illustrations.    By  J.  SOLIS 

COHEN,  M.  D.,  of  Philadelphia,  Lecturer  on  Diseases  of  the  Throat  in 
Jefferson  Medical  College. 

VI.  The  Winter  and  its  Dangers.    By  HAMILTON  OSGOOD,  M.  D., 

of  Boston,  Editorial  Staff  Boston  Medical  and  Surgical  Journal. 

VII.  The  Mouth  and  the  Teeth.    With  Illustrations.    By  J.  W. 

WHITE,  M.  D.,  D.  D.  S.,  of  Philadelphia,  Editor  of  the  Dental  Cosmos. 

VIII.  Brain  Work  and  Overwork.    By  H.  C.  WOOD,  JR.,  M.  D., 

of  Philadelphia,  Clinical  Professor  of  Nervous  Diseases  in  the  University 
of  Pennsylvania,  etc. 

IX.  Our  Homes.    With  Illustrations.    By  HENRY  HARTSHORNE,  M.  D., 

of  Philadelphia,  formerly  Professor  of  Hygiene  in  the  University  of 
Pennsylvania. 

X.  The  Skin  in  Health  and  Disease.  '  By  L.  D.  BULKLEY,  M.D., 

of  New  York,  Physician  to  the  Skin  Department  of  the  Demilt  Dispensary 
and  of  the  New  York  Hospital. 

XI.  Sea  Air  and  Sea  Bathing.    By  JOHN  H.  PACKARD,  M.  D., 

of  Philadelphia,  Surgeon  to  the  Episcopal  Hospital. 

XII.  School  and  Industrial  Hygiene.   By  D.  F.  LINCOLN,  M.  D., 

of  Boston,  Mass.,  Chairman  Department  of  Health,  American  Social 
Science  Association. 

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